diff --git a/CodeAnalysis/BannedSymbols.txt b/CodeAnalysis/BannedSymbols.txt
index 77197c4c51..8b5431e2d6 100644
--- a/CodeAnalysis/BannedSymbols.txt
+++ b/CodeAnalysis/BannedSymbols.txt
@@ -17,3 +17,5 @@ M:Realms.CollectionExtensions.SubscribeForNotifications`1(System.Collections.Gen
 M:System.Threading.Tasks.Task.Wait();Don't use Task.Wait. Use Task.WaitSafely() to ensure we avoid deadlocks.
 P:System.Threading.Tasks.Task`1.Result;Don't use Task.Result. Use Task.GetResultSafely() to ensure we avoid deadlocks.
 M:System.Threading.ManualResetEventSlim.Wait();Specify a timeout to avoid waiting forever.
+M:System.String.ToLower();string.ToLower() changes behaviour depending on CultureInfo.CurrentCulture. Use string.ToLowerInvariant() instead. If wanting culture-sensitive behaviour, explicitly provide CultureInfo.CurrentCulture or use LocalisableString.
+M:System.String.ToUpper();string.ToUpper() changes behaviour depending on CultureInfo.CurrentCulture. Use string.ToUpperInvariant() instead. If wanting culture-sensitive behaviour, explicitly provide CultureInfo.CurrentCulture or use LocalisableString.
diff --git a/osu.Game.Rulesets.Catch/CatchSkinComponent.cs b/osu.Game.Rulesets.Catch/CatchSkinComponent.cs
index 0fcdd34ca3..e79da667da 100644
--- a/osu.Game.Rulesets.Catch/CatchSkinComponent.cs
+++ b/osu.Game.Rulesets.Catch/CatchSkinComponent.cs
@@ -16,6 +16,6 @@ namespace osu.Game.Rulesets.Catch
 
         protected override string RulesetPrefix => "catch"; // todo: use CatchRuleset.SHORT_NAME;
 
-        protected override string ComponentName => Component.ToString().ToLower();
+        protected override string ComponentName => Component.ToString().ToLowerInvariant();
     }
 }
diff --git a/osu.Game.Rulesets.Mania/ManiaSkinComponent.cs b/osu.Game.Rulesets.Mania/ManiaSkinComponent.cs
index b709f85523..21b362df00 100644
--- a/osu.Game.Rulesets.Mania/ManiaSkinComponent.cs
+++ b/osu.Game.Rulesets.Mania/ManiaSkinComponent.cs
@@ -30,7 +30,7 @@ namespace osu.Game.Rulesets.Mania
 
         protected override string RulesetPrefix => ManiaRuleset.SHORT_NAME;
 
-        protected override string ComponentName => Component.ToString().ToLower();
+        protected override string ComponentName => Component.ToString().ToLowerInvariant();
     }
 
     public enum ManiaSkinComponents
diff --git a/osu.Game.Rulesets.Osu/OsuSkinComponent.cs b/osu.Game.Rulesets.Osu/OsuSkinComponent.cs
index 82c4005c5e..0abaf2c924 100644
--- a/osu.Game.Rulesets.Osu/OsuSkinComponent.cs
+++ b/osu.Game.Rulesets.Osu/OsuSkinComponent.cs
@@ -16,6 +16,6 @@ namespace osu.Game.Rulesets.Osu
 
         protected override string RulesetPrefix => OsuRuleset.SHORT_NAME;
 
-        protected override string ComponentName => Component.ToString().ToLower();
+        protected override string ComponentName => Component.ToString().ToLowerInvariant();
     }
 }
diff --git a/osu.Game.Rulesets.Taiko.Tests/Skinning/TestSceneDrawableTaikoMascot.cs b/osu.Game.Rulesets.Taiko.Tests/Skinning/TestSceneDrawableTaikoMascot.cs
index 1bf6c0560a..ef95358d34 100644
--- a/osu.Game.Rulesets.Taiko.Tests/Skinning/TestSceneDrawableTaikoMascot.cs
+++ b/osu.Game.Rulesets.Taiko.Tests/Skinning/TestSceneDrawableTaikoMascot.cs
@@ -144,7 +144,7 @@ namespace osu.Game.Rulesets.Taiko.Tests.Skinning
             createDrawableRuleset();
 
             assertStateAfterResult(new JudgementResult(new Swell(), new TaikoSwellJudgement()) { Type = HitResult.Great }, TaikoMascotAnimationState.Clear);
-            AddUntilStep($"state reverts to {expectedStateAfterClear.ToString().ToLower()}", () => allMascotsIn(expectedStateAfterClear));
+            AddUntilStep($"state reverts to {expectedStateAfterClear.ToString().ToLowerInvariant()}", () => allMascotsIn(expectedStateAfterClear));
         }
 
         private void setBeatmap(bool kiai = false)
@@ -195,7 +195,7 @@ namespace osu.Game.Rulesets.Taiko.Tests.Skinning
         {
             TaikoMascotAnimationState[] mascotStates = null;
 
-            AddStep($"{judgementResult.Type.ToString().ToLower()} result for {judgementResult.Judgement.GetType().Name.Humanize(LetterCasing.LowerCase)}",
+            AddStep($"{judgementResult.Type.ToString().ToLowerInvariant()} result for {judgementResult.Judgement.GetType().Name.Humanize(LetterCasing.LowerCase)}",
                 () =>
                 {
                     applyNewResult(judgementResult);
@@ -204,7 +204,7 @@ namespace osu.Game.Rulesets.Taiko.Tests.Skinning
                     Schedule(() => mascotStates = animatedMascots.Select(mascot => mascot.State.Value).ToArray());
                 });
 
-            AddAssert($"state is {expectedState.ToString().ToLower()}", () => mascotStates.All(state => state == expectedState));
+            AddAssert($"state is {expectedState.ToString().ToLowerInvariant()}", () => mascotStates.All(state => state == expectedState));
         }
 
         private void applyNewResult(JudgementResult judgementResult)
diff --git a/osu.Game.Rulesets.Taiko/TaikoSkinComponent.cs b/osu.Game.Rulesets.Taiko/TaikoSkinComponent.cs
index 676a3d4bc3..63314a6822 100644
--- a/osu.Game.Rulesets.Taiko/TaikoSkinComponent.cs
+++ b/osu.Game.Rulesets.Taiko/TaikoSkinComponent.cs
@@ -16,6 +16,6 @@ namespace osu.Game.Rulesets.Taiko
 
         protected override string RulesetPrefix => TaikoRuleset.SHORT_NAME;
 
-        protected override string ComponentName => Component.ToString().ToLower();
+        protected override string ComponentName => Component.ToString().ToLowerInvariant();
     }
 }
diff --git a/osu.Game.Rulesets.Taiko/UI/TaikoMascotAnimation.cs b/osu.Game.Rulesets.Taiko/UI/TaikoMascotAnimation.cs
index bacd9b41f8..26a37fc464 100644
--- a/osu.Game.Rulesets.Taiko/UI/TaikoMascotAnimation.cs
+++ b/osu.Game.Rulesets.Taiko/UI/TaikoMascotAnimation.cs
@@ -139,10 +139,10 @@ namespace osu.Game.Rulesets.Taiko.UI
 
         private static Texture getAnimationFrame(ISkin skin, TaikoMascotAnimationState state, int frameIndex)
         {
-            var texture = skin.GetTexture($"pippidon{state.ToString().ToLower()}{frameIndex}");
+            var texture = skin.GetTexture($"pippidon{state.ToString().ToLowerInvariant()}{frameIndex}");
 
             if (frameIndex == 0 && texture == null)
-                texture = skin.GetTexture($"pippidon{state.ToString().ToLower()}");
+                texture = skin.GetTexture($"pippidon{state.ToString().ToLowerInvariant()}");
 
             return texture;
         }
diff --git a/osu.Game.Tests/Gameplay/TestSceneDrainingHealthProcessor.cs b/osu.Game.Tests/Gameplay/TestSceneDrainingHealthProcessor.cs
index f9c4985219..c4e8bbfccf 100644
--- a/osu.Game.Tests/Gameplay/TestSceneDrainingHealthProcessor.cs
+++ b/osu.Game.Tests/Gameplay/TestSceneDrainingHealthProcessor.cs
@@ -192,7 +192,7 @@ namespace osu.Game.Tests.Gameplay
             AddStep("apply perfect hit result", () => processor.ApplyResult(new JudgementResult(beatmap.HitObjects[0], new Judgement()) { Type = HitResult.Perfect }));
             AddAssert("not failed", () => !processor.HasFailed);
 
-            AddStep($"apply {resultApplied.ToString().ToLower()} hit result", () => processor.ApplyResult(new JudgementResult(beatmap.HitObjects[0], new Judgement()) { Type = resultApplied }));
+            AddStep($"apply {resultApplied.ToString().ToLowerInvariant()} hit result", () => processor.ApplyResult(new JudgementResult(beatmap.HitObjects[0], new Judgement()) { Type = resultApplied }));
             AddAssert("failed", () => processor.HasFailed);
         }
 
diff --git a/osu.Game.Tests/NonVisual/CustomDataDirectoryTest.cs b/osu.Game.Tests/NonVisual/CustomDataDirectoryTest.cs
index 7d5f0bcd0c..a803974d30 100644
--- a/osu.Game.Tests/NonVisual/CustomDataDirectoryTest.cs
+++ b/osu.Game.Tests/NonVisual/CustomDataDirectoryTest.cs
@@ -254,7 +254,7 @@ namespace osu.Game.Tests.NonVisual
                     Assert.That(File.Exists(Path.Combine(customPath, OsuGameBase.CLIENT_DATABASE_FILENAME)));
 
                     Directory.CreateDirectory(customPath2);
-                    File.Copy(Path.Combine(customPath, OsuGameBase.CLIENT_DATABASE_FILENAME), Path.Combine(customPath2, OsuGameBase.CLIENT_DATABASE_FILENAME));
+                    File.WriteAllText(Path.Combine(customPath2, OsuGameBase.CLIENT_DATABASE_FILENAME), "I am a text");
 
                     // Fails because file already exists.
                     Assert.Throws<ArgumentException>(() => osu.Migrate(customPath2));
diff --git a/osu.Game.Tests/Visual/SongSelect/TestScenePlaySongSelect.cs b/osu.Game.Tests/Visual/SongSelect/TestScenePlaySongSelect.cs
index 9fcd470d17..6d881555da 100644
--- a/osu.Game.Tests/Visual/SongSelect/TestScenePlaySongSelect.cs
+++ b/osu.Game.Tests/Visual/SongSelect/TestScenePlaySongSelect.cs
@@ -872,10 +872,10 @@ namespace osu.Game.Tests.Visual.SongSelect
                 return set != null;
             });
 
-            FilterableGroupedDifficultyIcon groupIcon = null;
+            GroupedDifficultyIcon groupIcon = null;
             AddUntilStep("Find group icon for different ruleset", () =>
             {
-                return (groupIcon = set.ChildrenOfType<FilterableGroupedDifficultyIcon>()
+                return (groupIcon = set.ChildrenOfType<GroupedDifficultyIcon>()
                                        .FirstOrDefault(icon => icon.Items.First().BeatmapInfo.Ruleset.OnlineID == 3)) != null;
             });
 
diff --git a/osu.Game.Tournament/Models/TournamentTeam.cs b/osu.Game.Tournament/Models/TournamentTeam.cs
index 9dbe23b4b3..ac57f748da 100644
--- a/osu.Game.Tournament/Models/TournamentTeam.cs
+++ b/osu.Game.Tournament/Models/TournamentTeam.cs
@@ -66,14 +66,14 @@ namespace osu.Game.Tournament.Models
             {
                 // use a sane default flag name based on acronym.
                 if (val.OldValue.StartsWith(FlagName.Value, StringComparison.InvariantCultureIgnoreCase))
-                    FlagName.Value = val.NewValue.Length >= 2 ? val.NewValue?.Substring(0, 2).ToUpper() : string.Empty;
+                    FlagName.Value = val.NewValue.Length >= 2 ? val.NewValue?.Substring(0, 2).ToUpperInvariant() : string.Empty;
             };
 
             FullName.ValueChanged += val =>
             {
                 // use a sane acronym based on full name.
                 if (val.OldValue.StartsWith(Acronym.Value, StringComparison.InvariantCultureIgnoreCase))
-                    Acronym.Value = val.NewValue.Length >= 3 ? val.NewValue?.Substring(0, 3).ToUpper() : string.Empty;
+                    Acronym.Value = val.NewValue.Length >= 3 ? val.NewValue?.Substring(0, 3).ToUpperInvariant() : string.Empty;
             };
         }
 
diff --git a/osu.Game.Tournament/Screens/Ladder/Components/DrawableTournamentRound.cs b/osu.Game.Tournament/Screens/Ladder/Components/DrawableTournamentRound.cs
index ac196130d6..544725996a 100644
--- a/osu.Game.Tournament/Screens/Ladder/Components/DrawableTournamentRound.cs
+++ b/osu.Game.Tournament/Screens/Ladder/Components/DrawableTournamentRound.cs
@@ -49,10 +49,10 @@ namespace osu.Game.Tournament.Screens.Ladder.Components
             };
 
             name = round.Name.GetBoundCopy();
-            name.BindValueChanged(n => textName.Text = ((losers ? "Losers " : "") + round.Name).ToUpper(), true);
+            name.BindValueChanged(n => textName.Text = ((losers ? "Losers " : "") + round.Name).ToUpperInvariant(), true);
 
             description = round.Description.GetBoundCopy();
-            description.BindValueChanged(n => textDescription.Text = round.Description.Value?.ToUpper(), true);
+            description.BindValueChanged(n => textDescription.Text = round.Description.Value?.ToUpperInvariant(), true);
         }
     }
 }
diff --git a/osu.Game.Tournament/Screens/TeamIntro/SeedingScreen.cs b/osu.Game.Tournament/Screens/TeamIntro/SeedingScreen.cs
index df6e8e816e..925c697346 100644
--- a/osu.Game.Tournament/Screens/TeamIntro/SeedingScreen.cs
+++ b/osu.Game.Tournament/Screens/TeamIntro/SeedingScreen.cs
@@ -198,7 +198,7 @@ namespace osu.Game.Tournament.Screens.TeamIntro
                     {
                         row.Add(new Sprite
                         {
-                            Texture = textures.Get($"Mods/{mods.ToLower()}"),
+                            Texture = textures.Get($"Mods/{mods.ToLowerInvariant()}"),
                             Scale = new Vector2(0.5f)
                         });
                     }
diff --git a/osu.Game/Beatmaps/BeatmapDifficultyCache.cs b/osu.Game/Beatmaps/BeatmapDifficultyCache.cs
index 5e468e975a..ef0fa36b16 100644
--- a/osu.Game/Beatmaps/BeatmapDifficultyCache.cs
+++ b/osu.Game/Beatmaps/BeatmapDifficultyCache.cs
@@ -64,13 +64,13 @@ namespace osu.Game.Beatmaps
         {
             base.LoadComplete();
 
-            currentRuleset.BindValueChanged(_ => updateTrackedBindables());
+            currentRuleset.BindValueChanged(_ => Scheduler.AddOnce(updateTrackedBindables));
 
             currentMods.BindValueChanged(mods =>
             {
                 modSettingChangeTracker?.Dispose();
 
-                updateTrackedBindables();
+                Scheduler.AddOnce(updateTrackedBindables);
 
                 modSettingChangeTracker = new ModSettingChangeTracker(mods.NewValue);
                 modSettingChangeTracker.SettingChanged += _ =>
@@ -89,7 +89,9 @@ namespace osu.Game.Beatmaps
         /// <returns>A bindable that is updated to contain the star difficulty when it becomes available. Will be null while in an initial calculating state (but not during updates to ruleset and mods if a stale value is already propagated).</returns>
         public IBindable<StarDifficulty?> GetBindableDifficulty(IBeatmapInfo beatmapInfo, CancellationToken cancellationToken = default)
         {
-            var bindable = createBindable(beatmapInfo, currentRuleset.Value, currentMods.Value, cancellationToken);
+            var bindable = new BindableStarDifficulty(beatmapInfo, cancellationToken);
+
+            updateBindable(bindable, currentRuleset.Value, currentMods.Value, cancellationToken);
 
             lock (bindableUpdateLock)
                 trackedBindables.Add(bindable);
@@ -97,21 +99,6 @@ namespace osu.Game.Beatmaps
             return bindable;
         }
 
-        /// <summary>
-        /// Retrieves a bindable containing the star difficulty of a <see cref="IBeatmapInfo"/> with a given <see cref="RulesetInfo"/> and <see cref="Mod"/> combination.
-        /// </summary>
-        /// <remarks>
-        /// The bindable will not update to follow the currently-selected ruleset and mods or its settings.
-        /// </remarks>
-        /// <param name="beatmapInfo">The <see cref="IBeatmapInfo"/> to get the difficulty of.</param>
-        /// <param name="rulesetInfo">The <see cref="IRulesetInfo"/> to get the difficulty with. If <c>null</c>, the <paramref name="beatmapInfo"/>'s ruleset is used.</param>
-        /// <param name="mods">The <see cref="Mod"/>s to get the difficulty with. If <c>null</c>, no mods will be assumed.</param>
-        /// <param name="cancellationToken">An optional <see cref="CancellationToken"/> which stops updating the star difficulty for the given <see cref="IBeatmapInfo"/>.</param>
-        /// <returns>A bindable that is updated to contain the star difficulty when it becomes available. Will be null while in an initial calculating state.</returns>
-        public IBindable<StarDifficulty?> GetBindableDifficulty(IBeatmapInfo beatmapInfo, IRulesetInfo? rulesetInfo, IEnumerable<Mod>? mods,
-                                                                CancellationToken cancellationToken = default)
-            => createBindable(beatmapInfo, rulesetInfo, mods, cancellationToken);
-
         /// <summary>
         /// Retrieves the difficulty of a <see cref="IBeatmapInfo"/>.
         /// </summary>
@@ -200,22 +187,6 @@ namespace osu.Game.Beatmaps
             }
         }
 
-        /// <summary>
-        /// Creates a new <see cref="BindableStarDifficulty"/> and triggers an initial value update.
-        /// </summary>
-        /// <param name="beatmapInfo">The <see cref="IBeatmapInfo"/> that star difficulty should correspond to.</param>
-        /// <param name="initialRulesetInfo">The initial <see cref="IRulesetInfo"/> to get the difficulty with.</param>
-        /// <param name="initialMods">The initial <see cref="Mod"/>s to get the difficulty with.</param>
-        /// <param name="cancellationToken">An optional <see cref="CancellationToken"/> which stops updating the star difficulty for the given <see cref="IBeatmapInfo"/>.</param>
-        /// <returns>The <see cref="BindableStarDifficulty"/>.</returns>
-        private BindableStarDifficulty createBindable(IBeatmapInfo beatmapInfo, IRulesetInfo? initialRulesetInfo, IEnumerable<Mod>? initialMods,
-                                                      CancellationToken cancellationToken)
-        {
-            var bindable = new BindableStarDifficulty(beatmapInfo, cancellationToken);
-            updateBindable(bindable, initialRulesetInfo, initialMods, cancellationToken);
-            return bindable;
-        }
-
         /// <summary>
         /// Updates the value of a <see cref="BindableStarDifficulty"/> with a given ruleset + mods.
         /// </summary>
diff --git a/osu.Game/Beatmaps/BeatmapManager.cs b/osu.Game/Beatmaps/BeatmapManager.cs
index 816808638f..670dba14ec 100644
--- a/osu.Game/Beatmaps/BeatmapManager.cs
+++ b/osu.Game/Beatmaps/BeatmapManager.cs
@@ -418,22 +418,24 @@ namespace osu.Game.Beatmaps
 
         #region Implementation of IWorkingBeatmapCache
 
-        public WorkingBeatmap GetWorkingBeatmap(BeatmapInfo? importedBeatmap)
+        public WorkingBeatmap GetWorkingBeatmap(BeatmapInfo? beatmapInfo)
         {
             // Detached sets don't come with files.
             // If we seem to be missing files, now is a good time to re-fetch.
-            if (importedBeatmap?.BeatmapSet?.Files.Count == 0)
+            if (beatmapInfo?.IsManaged == true || beatmapInfo?.BeatmapSet?.Files.Count == 0)
             {
                 Realm.Run(r =>
                 {
-                    var refetch = r.Find<BeatmapInfo>(importedBeatmap.ID)?.Detach();
+                    var refetch = r.Find<BeatmapInfo>(beatmapInfo.ID)?.Detach();
 
                     if (refetch != null)
-                        importedBeatmap = refetch;
+                        beatmapInfo = refetch;
                 });
             }
 
-            return workingBeatmapCache.GetWorkingBeatmap(importedBeatmap);
+            Debug.Assert(beatmapInfo?.IsManaged != true);
+
+            return workingBeatmapCache.GetWorkingBeatmap(beatmapInfo);
         }
 
         void IWorkingBeatmapCache.Invalidate(BeatmapSetInfo beatmapSetInfo) => workingBeatmapCache.Invalidate(beatmapSetInfo);
diff --git a/osu.Game/Beatmaps/Drawables/Cards/Buttons/FavouriteButton.cs b/osu.Game/Beatmaps/Drawables/Cards/Buttons/FavouriteButton.cs
index 78481ac27a..bc0fcb92bb 100644
--- a/osu.Game/Beatmaps/Drawables/Cards/Buttons/FavouriteButton.cs
+++ b/osu.Game/Beatmaps/Drawables/Cards/Buttons/FavouriteButton.cs
@@ -64,7 +64,7 @@ namespace osu.Game.Beatmaps.Drawables.Cards.Buttons
             };
             favouriteRequest.Failure += e =>
             {
-                Logger.Error(e, $"Failed to {actionType.ToString().ToLower()} beatmap: {e.Message}");
+                Logger.Error(e, $"Failed to {actionType.ToString().ToLowerInvariant()} beatmap: {e.Message}");
                 Enabled.Value = true;
             };
 
diff --git a/osu.Game/Beatmaps/Drawables/DifficultyIcon.cs b/osu.Game/Beatmaps/Drawables/DifficultyIcon.cs
index a1b0f04aae..679e9c3665 100644
--- a/osu.Game/Beatmaps/Drawables/DifficultyIcon.cs
+++ b/osu.Game/Beatmaps/Drawables/DifficultyIcon.cs
@@ -1,12 +1,6 @@
-// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-#nullable disable
-
-using System;
-using System.Collections.Generic;
-using System.Threading;
-using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Extensions.Color4Extensions;
@@ -16,19 +10,17 @@ using osu.Framework.Graphics.Cursor;
 using osu.Framework.Graphics.Effects;
 using osu.Framework.Graphics.Shapes;
 using osu.Framework.Graphics.Sprites;
+using osu.Framework.Graphics.UserInterface;
 using osu.Game.Graphics;
 using osu.Game.Graphics.Containers;
 using osu.Game.Rulesets;
-using osu.Game.Rulesets.Mods;
 using osuTK;
 using osuTK.Graphics;
 
 namespace osu.Game.Beatmaps.Drawables
 {
-    public class DifficultyIcon : CompositeDrawable, IHasCustomTooltip<DifficultyIconTooltipContent>
+    public class DifficultyIcon : CompositeDrawable, IHasCustomTooltip<DifficultyIconTooltipContent>, IHasCurrentValue<StarDifficulty>
     {
-        private readonly Container iconContainer;
-
         /// <summary>
         /// Size of this difficulty icon.
         /// </summary>
@@ -38,57 +30,53 @@ namespace osu.Game.Beatmaps.Drawables
             set => iconContainer.Size = value;
         }
 
-        [NotNull]
-        private readonly IBeatmapInfo beatmapInfo;
+        /// <summary>
+        /// Whether to display a tooltip on hover. Only works if a beatmap was provided at construction time.
+        /// </summary>
+        public bool ShowTooltip { get; set; } = true;
+
+        private readonly IBeatmapInfo? beatmap;
 
-        [CanBeNull]
         private readonly IRulesetInfo ruleset;
 
-        [CanBeNull]
-        private readonly IReadOnlyList<Mod> mods;
+        private Drawable background = null!;
 
-        private readonly bool shouldShowTooltip;
+        private readonly Container iconContainer;
 
-        private readonly bool performBackgroundDifficultyLookup;
+        private readonly BindableWithCurrent<StarDifficulty> difficulty = new BindableWithCurrent<StarDifficulty>();
 
-        private readonly Bindable<StarDifficulty> difficultyBindable = new Bindable<StarDifficulty>();
-
-        private Drawable background;
-
-        /// <summary>
-        /// Creates a new <see cref="DifficultyIcon"/> with a given <see cref="RulesetInfo"/> and <see cref="Mod"/> combination.
-        /// </summary>
-        /// <param name="beatmapInfo">The beatmap to show the difficulty of.</param>
-        /// <param name="ruleset">The ruleset to show the difficulty with.</param>
-        /// <param name="mods">The mods to show the difficulty with.</param>
-        /// <param name="shouldShowTooltip">Whether to display a tooltip when hovered.</param>
-        /// <param name="performBackgroundDifficultyLookup">Whether to perform difficulty lookup (including calculation if necessary).</param>
-        public DifficultyIcon([NotNull] IBeatmapInfo beatmapInfo, [CanBeNull] IRulesetInfo ruleset, [CanBeNull] IReadOnlyList<Mod> mods, bool shouldShowTooltip = true, bool performBackgroundDifficultyLookup = true)
-            : this(beatmapInfo, shouldShowTooltip, performBackgroundDifficultyLookup)
+        public virtual Bindable<StarDifficulty> Current
         {
-            this.ruleset = ruleset ?? beatmapInfo.Ruleset;
-            this.mods = mods ?? Array.Empty<Mod>();
-        }
-
-        /// <summary>
-        /// Creates a new <see cref="DifficultyIcon"/> that follows the currently-selected ruleset and mods.
-        /// </summary>
-        /// <param name="beatmapInfo">The beatmap to show the difficulty of.</param>
-        /// <param name="shouldShowTooltip">Whether to display a tooltip when hovered.</param>
-        /// <param name="performBackgroundDifficultyLookup">Whether to perform difficulty lookup (including calculation if necessary).</param>
-        public DifficultyIcon([NotNull] IBeatmapInfo beatmapInfo, bool shouldShowTooltip = true, bool performBackgroundDifficultyLookup = true)
-        {
-            this.beatmapInfo = beatmapInfo ?? throw new ArgumentNullException(nameof(beatmapInfo));
-            this.shouldShowTooltip = shouldShowTooltip;
-            this.performBackgroundDifficultyLookup = performBackgroundDifficultyLookup;
-
-            AutoSizeAxes = Axes.Both;
-
-            InternalChild = iconContainer = new Container { Size = new Vector2(20f) };
+            get => difficulty.Current;
+            set => difficulty.Current = value;
         }
 
         [Resolved]
-        private IRulesetStore rulesets { get; set; }
+        private IRulesetStore rulesets { get; set; } = null!;
+
+        /// <summary>
+        /// Creates a new <see cref="DifficultyIcon"/>. Will use provided beatmap's <see cref="BeatmapInfo.StarRating"/> for initial value.
+        /// </summary>
+        /// <param name="beatmap">The beatmap to be displayed in the tooltip, and to be used for the initial star rating value.</param>
+        /// <param name="ruleset">An optional ruleset to be used for the icon display, in place of the beatmap's ruleset.</param>
+        public DifficultyIcon(IBeatmapInfo beatmap, IRulesetInfo? ruleset = null)
+            : this(ruleset ?? beatmap.Ruleset)
+        {
+            this.beatmap = beatmap;
+            Current.Value = new StarDifficulty(beatmap.StarRating, 0);
+        }
+
+        /// <summary>
+        /// Creates a new <see cref="DifficultyIcon"/> without an associated beatmap.
+        /// </summary>
+        /// <param name="ruleset">The ruleset to be used for the icon display.</param>
+        public DifficultyIcon(IRulesetInfo ruleset)
+        {
+            this.ruleset = ruleset;
+
+            AutoSizeAxes = Axes.Both;
+            InternalChild = iconContainer = new Container { Size = new Vector2(20f) };
+        }
 
         [BackgroundDependencyLoader]
         private void load(OsuColour colours)
@@ -111,7 +99,6 @@ namespace osu.Game.Beatmaps.Drawables
                     Child = background = new Box
                     {
                         RelativeSizeAxes = Axes.Both,
-                        Colour = colours.ForStarDifficulty(beatmapInfo.StarRating) // Default value that will be re-populated once difficulty calculation completes
                     },
                 },
                 new ConstrainedIconContainer
@@ -124,17 +111,12 @@ namespace osu.Game.Beatmaps.Drawables
                 },
             };
 
-            if (performBackgroundDifficultyLookup)
-                iconContainer.Add(new DelayedLoadUnloadWrapper(() => new DifficultyRetriever(beatmapInfo, ruleset, mods) { StarDifficulty = { BindTarget = difficultyBindable } }, 0));
-            else
-                difficultyBindable.Value = new StarDifficulty(beatmapInfo.StarRating, 0);
-
-            difficultyBindable.BindValueChanged(difficulty => background.Colour = colours.ForStarDifficulty(difficulty.NewValue.Stars));
+            Current.BindValueChanged(difficulty => background.Colour = colours.ForStarDifficulty(difficulty.NewValue.Stars), true);
         }
 
         private Drawable getRulesetIcon()
         {
-            int? onlineID = (ruleset ?? beatmapInfo.Ruleset).OnlineID;
+            int? onlineID = ruleset.OnlineID;
 
             if (onlineID >= 0 && rulesets.GetRuleset(onlineID.Value)?.CreateInstance() is Ruleset rulesetInstance)
                 return rulesetInstance.CreateIcon();
@@ -142,51 +124,10 @@ namespace osu.Game.Beatmaps.Drawables
             return new SpriteIcon { Icon = FontAwesome.Regular.QuestionCircle };
         }
 
-        ITooltip<DifficultyIconTooltipContent> IHasCustomTooltip<DifficultyIconTooltipContent>.GetCustomTooltip() => new DifficultyIconTooltip();
+        ITooltip<DifficultyIconTooltipContent> IHasCustomTooltip<DifficultyIconTooltipContent>.
+            GetCustomTooltip() => new DifficultyIconTooltip();
 
-        DifficultyIconTooltipContent IHasCustomTooltip<DifficultyIconTooltipContent>.TooltipContent => shouldShowTooltip ? new DifficultyIconTooltipContent(beatmapInfo, difficultyBindable) : null;
-
-        private class DifficultyRetriever : Component
-        {
-            public readonly Bindable<StarDifficulty> StarDifficulty = new Bindable<StarDifficulty>();
-
-            private readonly IBeatmapInfo beatmapInfo;
-            private readonly IRulesetInfo ruleset;
-            private readonly IReadOnlyList<Mod> mods;
-
-            private CancellationTokenSource difficultyCancellation;
-
-            [Resolved]
-            private BeatmapDifficultyCache difficultyCache { get; set; }
-
-            public DifficultyRetriever(IBeatmapInfo beatmapInfo, IRulesetInfo ruleset, IReadOnlyList<Mod> mods)
-            {
-                this.beatmapInfo = beatmapInfo;
-                this.ruleset = ruleset;
-                this.mods = mods;
-            }
-
-            private IBindable<StarDifficulty?> localStarDifficulty;
-
-            [BackgroundDependencyLoader]
-            private void load()
-            {
-                difficultyCancellation = new CancellationTokenSource();
-                localStarDifficulty = ruleset != null
-                    ? difficultyCache.GetBindableDifficulty(beatmapInfo, ruleset, mods, difficultyCancellation.Token)
-                    : difficultyCache.GetBindableDifficulty(beatmapInfo, difficultyCancellation.Token);
-                localStarDifficulty.BindValueChanged(d =>
-                {
-                    if (d.NewValue is StarDifficulty diff)
-                        StarDifficulty.Value = diff;
-                });
-            }
-
-            protected override void Dispose(bool isDisposing)
-            {
-                base.Dispose(isDisposing);
-                difficultyCancellation?.Cancel();
-            }
-        }
+        DifficultyIconTooltipContent IHasCustomTooltip<DifficultyIconTooltipContent>.
+            TooltipContent => (ShowTooltip && beatmap != null ? new DifficultyIconTooltipContent(beatmap, Current) : null)!;
     }
 }
diff --git a/osu.Game/Beatmaps/Drawables/GroupedDifficultyIcon.cs b/osu.Game/Beatmaps/Drawables/GroupedDifficultyIcon.cs
deleted file mode 100644
index 15ca4c60d4..0000000000
--- a/osu.Game/Beatmaps/Drawables/GroupedDifficultyIcon.cs
+++ /dev/null
@@ -1,39 +0,0 @@
-// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
-// See the LICENCE file in the repository root for full licence text.
-
-#nullable disable
-
-using System.Collections.Generic;
-using System.Linq;
-using osu.Framework.Graphics;
-using osu.Game.Graphics;
-using osu.Game.Graphics.Sprites;
-using osu.Game.Rulesets;
-using osuTK.Graphics;
-
-namespace osu.Game.Beatmaps.Drawables
-{
-    /// <summary>
-    /// A difficulty icon that contains a counter on the right-side of it.
-    /// </summary>
-    /// <remarks>
-    /// Used in cases when there are too many difficulty icons to show.
-    /// </remarks>
-    public class GroupedDifficultyIcon : DifficultyIcon
-    {
-        public GroupedDifficultyIcon(IEnumerable<IBeatmapInfo> beatmaps, IRulesetInfo ruleset, Color4 counterColour)
-            : base(beatmaps.OrderBy(b => b.StarRating).Last(), ruleset, null, false)
-        {
-            AddInternal(new OsuSpriteText
-            {
-                Anchor = Anchor.CentreRight,
-                Origin = Anchor.CentreRight,
-                Padding = new MarginPadding { Left = Size.X },
-                Margin = new MarginPadding { Left = 2, Right = 5 },
-                Font = OsuFont.GetFont(size: 14, weight: FontWeight.SemiBold),
-                Text = beatmaps.Count().ToString(),
-                Colour = counterColour,
-            });
-        }
-    }
-}
diff --git a/osu.Game/Database/IModelImporter.cs b/osu.Game/Database/IModelImporter.cs
index 26342cb5fe..ebb8be39ef 100644
--- a/osu.Game/Database/IModelImporter.cs
+++ b/osu.Game/Database/IModelImporter.cs
@@ -26,7 +26,7 @@ namespace osu.Game.Database
         /// <summary>
         /// A user displayable name for the model type associated with this manager.
         /// </summary>
-        string HumanisedModelName => $"{typeof(TModel).Name.Replace(@"Info", "").ToLower()}";
+        string HumanisedModelName => $"{typeof(TModel).Name.Replace(@"Info", "").ToLowerInvariant()}";
 
         /// <summary>
         /// Fired when the user requests to view the resulting import.
diff --git a/osu.Game/Database/ModelManager.cs b/osu.Game/Database/ModelManager.cs
index e0c3dccf57..9603412178 100644
--- a/osu.Game/Database/ModelManager.cs
+++ b/osu.Game/Database/ModelManager.cs
@@ -201,6 +201,6 @@ namespace osu.Game.Database
 
         public Action<Notification>? PostNotification { get; set; }
 
-        public virtual string HumanisedModelName => $"{typeof(TModel).Name.Replace(@"Info", "").ToLower()}";
+        public virtual string HumanisedModelName => $"{typeof(TModel).Name.Replace(@"Info", "").ToLowerInvariant()}";
     }
 }
diff --git a/osu.Game/Database/RealmArchiveModelImporter.cs b/osu.Game/Database/RealmArchiveModelImporter.cs
index 27bfaf05be..a3349d9918 100644
--- a/osu.Game/Database/RealmArchiveModelImporter.cs
+++ b/osu.Game/Database/RealmArchiveModelImporter.cs
@@ -549,6 +549,6 @@ namespace osu.Game.Database
                 yield return f.Filename;
         }
 
-        public virtual string HumanisedModelName => $"{typeof(TModel).Name.Replace(@"Info", "").ToLower()}";
+        public virtual string HumanisedModelName => $"{typeof(TModel).Name.Replace(@"Info", "").ToLowerInvariant()}";
     }
 }
diff --git a/osu.Game/Online/API/Requests/GetSpotlightRankingsRequest.cs b/osu.Game/Online/API/Requests/GetSpotlightRankingsRequest.cs
index 75b0cf8027..2d8a8b3b61 100644
--- a/osu.Game/Online/API/Requests/GetSpotlightRankingsRequest.cs
+++ b/osu.Game/Online/API/Requests/GetSpotlightRankingsRequest.cs
@@ -26,7 +26,7 @@ namespace osu.Game.Online.API.Requests
             var req = base.CreateWebRequest();
 
             req.AddParameter("spotlight", spotlight.ToString());
-            req.AddParameter("filter", sort.ToString().ToLower());
+            req.AddParameter("filter", sort.ToString().ToLowerInvariant());
 
             return req;
         }
diff --git a/osu.Game/Online/API/Requests/GetUserRequest.cs b/osu.Game/Online/API/Requests/GetUserRequest.cs
index ab45e8e48f..7dcf75950e 100644
--- a/osu.Game/Online/API/Requests/GetUserRequest.cs
+++ b/osu.Game/Online/API/Requests/GetUserRequest.cs
@@ -45,7 +45,7 @@ namespace osu.Game.Online.API.Requests
             Ruleset = ruleset;
         }
 
-        protected override string Target => Lookup != null ? $@"users/{Lookup}/{Ruleset?.ShortName}?key={lookupType.ToString().ToLower()}" : $@"me/{Ruleset?.ShortName}";
+        protected override string Target => Lookup != null ? $@"users/{Lookup}/{Ruleset?.ShortName}?key={lookupType.ToString().ToLowerInvariant()}" : $@"me/{Ruleset?.ShortName}";
 
         private enum LookupType
         {
diff --git a/osu.Game/Online/Leaderboards/UserTopScoreContainer.cs b/osu.Game/Online/Leaderboards/UserTopScoreContainer.cs
index df8717fe6d..2d2d82821c 100644
--- a/osu.Game/Online/Leaderboards/UserTopScoreContainer.cs
+++ b/osu.Game/Online/Leaderboards/UserTopScoreContainer.cs
@@ -48,7 +48,7 @@ namespace osu.Game.Online.Leaderboards
                         {
                             Anchor = Anchor.TopCentre,
                             Origin = Anchor.TopCentre,
-                            Text = @"your personal best".ToUpper(),
+                            Text = @"your personal best".ToUpperInvariant(),
                             Font = OsuFont.GetFont(size: 15, weight: FontWeight.Bold),
                         },
                         scoreContainer = new Container
diff --git a/osu.Game/Overlays/BeatmapSet/BeatmapPicker.cs b/osu.Game/Overlays/BeatmapSet/BeatmapPicker.cs
index 8d89bb3cc7..1a57a89957 100644
--- a/osu.Game/Overlays/BeatmapSet/BeatmapPicker.cs
+++ b/osu.Game/Overlays/BeatmapSet/BeatmapPicker.cs
@@ -274,8 +274,10 @@ namespace osu.Game.Overlays.BeatmapSet
                             Alpha = 0.5f
                         }
                     },
-                    icon = new DifficultyIcon(beatmapInfo, shouldShowTooltip: false)
+                    icon = new DifficultyIcon(beatmapInfo)
                     {
+                        ShowTooltip = false,
+                        Current = { Value = new StarDifficulty(beatmapInfo.StarRating, 0) },
                         Anchor = Anchor.Centre,
                         Origin = Anchor.Centre,
                         Size = new Vector2(size - tile_icon_padding * 2),
diff --git a/osu.Game/Overlays/Chat/DaySeparator.cs b/osu.Game/Overlays/Chat/DaySeparator.cs
index c7961d1a39..be0b53785c 100644
--- a/osu.Game/Overlays/Chat/DaySeparator.cs
+++ b/osu.Game/Overlays/Chat/DaySeparator.cs
@@ -3,6 +3,7 @@
 
 using System;
 using osu.Framework.Allocation;
+using osu.Framework.Extensions.LocalisationExtensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Shapes;
@@ -79,7 +80,7 @@ namespace osu.Game.Overlays.Chat
                                     {
                                         Anchor = Anchor.CentreRight,
                                         Origin = Anchor.CentreRight,
-                                        Text = time.ToLocalTime().ToString("dd MMMM yyyy").ToUpper(),
+                                        Text = time.ToLocalTime().ToLocalisableString(@"dd MMMM yyyy").ToUpper(),
                                         Font = OsuFont.Torus.With(size: TextSize, weight: FontWeight.SemiBold),
                                         Colour = colourProvider?.Content1 ?? Colour4.White,
                                     },
diff --git a/osu.Game/Overlays/News/NewsCard.cs b/osu.Game/Overlays/News/NewsCard.cs
index 69094a0df7..eb76522e11 100644
--- a/osu.Game/Overlays/News/NewsCard.cs
+++ b/osu.Game/Overlays/News/NewsCard.cs
@@ -7,6 +7,7 @@ using System;
 using System.Collections.Generic;
 using osu.Framework.Allocation;
 using osu.Framework.Extensions.Color4Extensions;
+using osu.Framework.Extensions.LocalisationExtensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Cursor;
@@ -146,7 +147,7 @@ namespace osu.Game.Overlays.News
                     },
                     new OsuSpriteText
                     {
-                        Text = date.ToString("d MMM yyyy").ToUpper(),
+                        Text = date.ToLocalisableString(@"d MMM yyyy").ToUpper(),
                         Font = OsuFont.GetFont(size: 10, weight: FontWeight.SemiBold),
                         Margin = new MarginPadding
                         {
diff --git a/osu.Game/Overlays/TabControlOverlayHeader.cs b/osu.Game/Overlays/TabControlOverlayHeader.cs
index 4e32afb86f..84a5bf1144 100644
--- a/osu.Game/Overlays/TabControlOverlayHeader.cs
+++ b/osu.Game/Overlays/TabControlOverlayHeader.cs
@@ -109,15 +109,15 @@ namespace osu.Game.Overlays
                     : base(value)
                 {
                     if (!(Value is Enum enumValue))
-                        Text.Text = Value.ToString().ToLower();
+                        Text.Text = Value.ToString().ToLowerInvariant();
                     else
                     {
                         var localisableDescription = enumValue.GetLocalisableDescription();
                         string nonLocalisableDescription = enumValue.GetDescription();
 
-                        // If localisable == non-localisable, then we must have a basic string, so .ToLower() is used.
+                        // If localisable == non-localisable, then we must have a basic string, so .ToLowerInvariant() is used.
                         Text.Text = localisableDescription.Equals(nonLocalisableDescription)
-                            ? nonLocalisableDescription.ToLower()
+                            ? nonLocalisableDescription.ToLowerInvariant()
                             : localisableDescription;
                     }
 
diff --git a/osu.Game/Rulesets/Edit/Checks/CheckMutedObjects.cs b/osu.Game/Rulesets/Edit/Checks/CheckMutedObjects.cs
index cb6c4a9928..00b1ca9dc9 100644
--- a/osu.Game/Rulesets/Edit/Checks/CheckMutedObjects.cs
+++ b/osu.Game/Rulesets/Edit/Checks/CheckMutedObjects.cs
@@ -74,7 +74,7 @@ namespace osu.Game.Rulesets.Edit.Checks
             if (edgeType == EdgeType.None)
                 yield break;
 
-            string postfix = hitObject is IHasDuration ? edgeType.ToString().ToLower() : null;
+            string postfix = hitObject is IHasDuration ? edgeType.ToString().ToLowerInvariant() : null;
 
             if (maxVolume <= muted_threshold)
             {
diff --git a/osu.Game/Rulesets/Edit/Checks/CheckTooShortAudioFiles.cs b/osu.Game/Rulesets/Edit/Checks/CheckTooShortAudioFiles.cs
index a461f63d2d..2a222aece0 100644
--- a/osu.Game/Rulesets/Edit/Checks/CheckTooShortAudioFiles.cs
+++ b/osu.Game/Rulesets/Edit/Checks/CheckTooShortAudioFiles.cs
@@ -65,7 +65,7 @@ namespace osu.Game.Rulesets.Edit.Checks
             }
         }
 
-        private bool hasAudioExtension(string filename) => audioExtensions.Any(filename.ToLower().EndsWith);
+        private bool hasAudioExtension(string filename) => audioExtensions.Any(filename.ToLowerInvariant().EndsWith);
         private bool probablyHasAudioData(Stream data) => data.Length > min_bytes_threshold;
 
         public class IssueTemplateTooShort : IssueTemplate
diff --git a/osu.Game/Screens/OnlinePlay/Components/ModeTypeInfo.cs b/osu.Game/Screens/OnlinePlay/Components/ModeTypeInfo.cs
deleted file mode 100644
index 641776a9e8..0000000000
--- a/osu.Game/Screens/OnlinePlay/Components/ModeTypeInfo.cs
+++ /dev/null
@@ -1,78 +0,0 @@
-// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
-// See the LICENCE file in the repository root for full licence text.
-
-#nullable disable
-
-using System.Linq;
-using osu.Framework.Allocation;
-using osu.Framework.Graphics;
-using osu.Framework.Graphics.Containers;
-using osu.Game.Beatmaps.Drawables;
-using osu.Game.Rulesets;
-using osuTK;
-
-namespace osu.Game.Screens.OnlinePlay.Components
-{
-    public class ModeTypeInfo : OnlinePlayComposite
-    {
-        private const float height = 28;
-        private const float transition_duration = 100;
-
-        [Resolved]
-        private RulesetStore rulesets { get; set; }
-
-        private Container drawableRuleset;
-
-        public ModeTypeInfo()
-        {
-            AutoSizeAxes = Axes.Both;
-        }
-
-        [BackgroundDependencyLoader]
-        private void load()
-        {
-            Container gameTypeContainer;
-
-            InternalChild = new FillFlowContainer
-            {
-                AutoSizeAxes = Axes.Both,
-                Direction = FillDirection.Horizontal,
-                Spacing = new Vector2(5f, 0f),
-                LayoutDuration = 100,
-                Children = new[]
-                {
-                    drawableRuleset = new Container
-                    {
-                        AutoSizeAxes = Axes.Both,
-                    },
-                    gameTypeContainer = new Container
-                    {
-                        AutoSizeAxes = Axes.Both,
-                    },
-                },
-            };
-
-            Type.BindValueChanged(type => gameTypeContainer.Child = new DrawableGameType(type.NewValue) { Size = new Vector2(height) }, true);
-
-            Playlist.CollectionChanged += (_, __) => updateBeatmap();
-
-            updateBeatmap();
-        }
-
-        private void updateBeatmap()
-        {
-            var item = Playlist.FirstOrDefault();
-            var ruleset = item == null ? null : rulesets.GetRuleset(item.RulesetID)?.CreateInstance();
-
-            if (item?.Beatmap != null && ruleset != null)
-            {
-                var mods = item.RequiredMods.Select(m => m.ToMod(ruleset)).ToArray();
-
-                drawableRuleset.FadeIn(transition_duration);
-                drawableRuleset.Child = new DifficultyIcon(item.Beatmap, ruleset.RulesetInfo, mods) { Size = new Vector2(height) };
-            }
-            else
-                drawableRuleset.FadeOut(transition_duration);
-        }
-    }
-}
diff --git a/osu.Game/Screens/OnlinePlay/DrawableRoomPlaylistItem.cs b/osu.Game/Screens/OnlinePlay/DrawableRoomPlaylistItem.cs
index 53519b8b00..a3a176477e 100644
--- a/osu.Game/Screens/OnlinePlay/DrawableRoomPlaylistItem.cs
+++ b/osu.Game/Screens/OnlinePlay/DrawableRoomPlaylistItem.cs
@@ -266,7 +266,7 @@ namespace osu.Game.Screens.OnlinePlay
             }
 
             if (beatmap != null)
-                difficultyIconContainer.Child = new DifficultyIcon(beatmap, ruleset, requiredMods, performBackgroundDifficultyLookup: false) { Size = new Vector2(icon_height) };
+                difficultyIconContainer.Child = new DifficultyIcon(beatmap, ruleset) { Size = new Vector2(icon_height) };
             else
                 difficultyIconContainer.Clear();
 
diff --git a/osu.Game/Screens/OnlinePlay/Match/Components/RoomSettingsOverlay.cs b/osu.Game/Screens/OnlinePlay/Match/Components/RoomSettingsOverlay.cs
index c295e9f85e..71447b15e2 100644
--- a/osu.Game/Screens/OnlinePlay/Match/Components/RoomSettingsOverlay.cs
+++ b/osu.Game/Screens/OnlinePlay/Match/Components/RoomSettingsOverlay.cs
@@ -135,7 +135,7 @@ namespace osu.Game.Screens.OnlinePlay.Match.Components
                         new OsuSpriteText
                         {
                             Font = OsuFont.GetFont(weight: FontWeight.Bold, size: 12),
-                            Text = title.ToUpper(),
+                            Text = title.ToUpperInvariant(),
                         },
                         content = new Container
                         {
diff --git a/osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmap.cs b/osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmap.cs
index 1bea689e7c..1b3cab20e8 100644
--- a/osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmap.cs
+++ b/osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmap.cs
@@ -53,7 +53,9 @@ namespace osu.Game.Screens.Select.Carousel
         private Action<BeatmapInfo> hideRequested;
 
         private Triangles triangles;
+
         private StarCounter starCounter;
+        private DifficultyIcon difficultyIcon;
 
         [Resolved(CanBeNull = true)]
         private BeatmapSetOverlay beatmapOverlay { get; set; }
@@ -113,8 +115,9 @@ namespace osu.Game.Screens.Select.Carousel
                     Origin = Anchor.CentreLeft,
                     Children = new Drawable[]
                     {
-                        new DifficultyIcon(beatmapInfo, shouldShowTooltip: false)
+                        difficultyIcon = new DifficultyIcon(beatmapInfo)
                         {
+                            ShowTooltip = false,
                             Scale = new Vector2(1.8f),
                         },
                         new FillFlowContainer
@@ -216,6 +219,8 @@ namespace osu.Game.Screens.Select.Carousel
                 starDifficultyBindable.BindValueChanged(d =>
                 {
                     starCounter.Current = (float)(d.NewValue?.Stars ?? 0);
+                    if (d.NewValue != null)
+                        difficultyIcon.Current.Value = d.NewValue.Value;
                 }, true);
             }
 
diff --git a/osu.Game/Screens/Select/Carousel/FilterableDifficultyIcon.cs b/osu.Game/Screens/Select/Carousel/FilterableDifficultyIcon.cs
index b0841caa47..cc904fc1da 100644
--- a/osu.Game/Screens/Select/Carousel/FilterableDifficultyIcon.cs
+++ b/osu.Game/Screens/Select/Carousel/FilterableDifficultyIcon.cs
@@ -19,7 +19,7 @@ namespace osu.Game.Screens.Select.Carousel
         public readonly CarouselBeatmap Item;
 
         public FilterableDifficultyIcon(CarouselBeatmap item)
-            : base(item.BeatmapInfo, performBackgroundDifficultyLookup: false)
+            : base(item.BeatmapInfo)
         {
             filtered.BindTo(item.Filtered);
             filtered.ValueChanged += isFiltered => Schedule(() => this.FadeTo(isFiltered.NewValue ? 0.1f : 1, 100));
diff --git a/osu.Game/Screens/Select/Carousel/FilterableGroupedDifficultyIcon.cs b/osu.Game/Screens/Select/Carousel/GroupedDifficultyIcon.cs
similarity index 53%
rename from osu.Game/Screens/Select/Carousel/FilterableGroupedDifficultyIcon.cs
rename to osu.Game/Screens/Select/Carousel/GroupedDifficultyIcon.cs
index f883740fd7..8b4140df56 100644
--- a/osu.Game/Screens/Select/Carousel/FilterableGroupedDifficultyIcon.cs
+++ b/osu.Game/Screens/Select/Carousel/GroupedDifficultyIcon.cs
@@ -8,23 +8,42 @@ using System.Linq;
 using osu.Framework.Graphics;
 using osu.Framework.Input.Events;
 using osu.Game.Beatmaps.Drawables;
+using osu.Game.Graphics;
+using osu.Game.Graphics.Sprites;
 using osu.Game.Rulesets;
 using osuTK.Graphics;
 
 namespace osu.Game.Screens.Select.Carousel
 {
-    public class FilterableGroupedDifficultyIcon : GroupedDifficultyIcon
+    /// <summary>
+    /// A difficulty icon that contains a counter on the right-side of it.
+    /// </summary>
+    /// <remarks>
+    /// Used in cases when there are too many difficulty icons to show.
+    /// </remarks>
+    public class GroupedDifficultyIcon : DifficultyIcon
     {
         public readonly List<CarouselBeatmap> Items;
 
-        public FilterableGroupedDifficultyIcon(List<CarouselBeatmap> items, RulesetInfo ruleset)
-            : base(items.Select(i => i.BeatmapInfo).ToList(), ruleset, Color4.White)
+        public GroupedDifficultyIcon(List<CarouselBeatmap> items, RulesetInfo ruleset)
+            : base(items.OrderBy(b => b.BeatmapInfo.StarRating).Last().BeatmapInfo, ruleset)
         {
             Items = items;
 
             foreach (var item in items)
                 item.Filtered.BindValueChanged(_ => Scheduler.AddOnce(updateFilteredDisplay));
 
+            AddInternal(new OsuSpriteText
+            {
+                Anchor = Anchor.CentreRight,
+                Origin = Anchor.CentreRight,
+                Padding = new MarginPadding { Left = Size.X },
+                Margin = new MarginPadding { Left = 2, Right = 5 },
+                Font = OsuFont.GetFont(size: 14, weight: FontWeight.SemiBold),
+                Text = items.Count.ToString(),
+                Colour = Color4.White,
+            });
+
             updateFilteredDisplay();
         }
 
diff --git a/osu.Game/Screens/Select/Carousel/SetPanelContent.cs b/osu.Game/Screens/Select/Carousel/SetPanelContent.cs
index 0400e2c938..577b3f5f64 100644
--- a/osu.Game/Screens/Select/Carousel/SetPanelContent.cs
+++ b/osu.Game/Screens/Select/Carousel/SetPanelContent.cs
@@ -93,7 +93,7 @@ namespace osu.Game.Screens.Select.Carousel
 
             return beatmaps.Count > maximum_difficulty_icons
                 ? beatmaps.GroupBy(b => b.BeatmapInfo.Ruleset)
-                          .Select(group => new FilterableGroupedDifficultyIcon(group.ToList(), group.Last().BeatmapInfo.Ruleset))
+                          .Select(group => new GroupedDifficultyIcon(group.ToList(), group.Last().BeatmapInfo.Ruleset))
                 : beatmaps.Select(b => new FilterableDifficultyIcon(b));
         }
     }
diff --git a/osu.Game/Screens/Select/FilterQueryParser.cs b/osu.Game/Screens/Select/FilterQueryParser.cs
index 92f707ae3e..03b72bf5e9 100644
--- a/osu.Game/Screens/Select/FilterQueryParser.cs
+++ b/osu.Game/Screens/Select/FilterQueryParser.cs
@@ -24,7 +24,7 @@ namespace osu.Game.Screens.Select
         {
             foreach (Match match in query_syntax_regex.Matches(query))
             {
-                string key = match.Groups["key"].Value.ToLower();
+                string key = match.Groups["key"].Value.ToLowerInvariant();
                 var op = parseOperator(match.Groups["op"].Value);
                 string value = match.Groups["value"].Value;