Use hashset for faster lookup

Author: bdach

osu.Game/Screens/Select/FilterControl.cs

@@ -4,7 +4,7 @@
 #nullable disable
 
 using System;
-using System.Linq;
+using System.Collections.Immutable;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
@@ -65,7 +65,7 @@ public FilterCriteria CreateCriteria()
                 Sort = sortMode.Value,
                 AllowConvertedBeatmaps = showConverted.Value,
                 Ruleset = ruleset.Value,
-                CollectionBeatmapMD5Hashes = collectionDropdown.Current.Value?.Collection?.PerformRead(c => c.BeatmapMD5Hashes).ToList()
+                CollectionBeatmapMD5Hashes = collectionDropdown.Current.Value?.Collection?.PerformRead(c => c.BeatmapMD5Hashes).ToImmutableHashSet()
             };
 
             if (!minimumStars.IsDefault)