Major performance optimizations for beatmap parsing and difficulty calculation

Templates/Rulesets/ruleset-empty/osu.Game.Rulesets.EmptyFreeform/EmptyFreeformDifficultyCalculator.cs

@@ -27,5 +27,6 @@ protected override DifficultyAttributes CreateDifficultyAttributes(IBeatmap beat
         protected override IEnumerable<DifficultyHitObject> CreateDifficultyHitObjects(IBeatmap beatmap, double clockRate) => [];
 
         protected override Skill[] CreateSkills(IBeatmap beatmap, Mod[] mods, double clockRate) => [];
+        protected override DifficultyAttributes CreateEmptyAttributes() => new DifficultyAttributes();
     }
 }

Templates/Rulesets/ruleset-example/osu.Game.Rulesets.Pippidon/PippidonDifficultyCalculator.cs

@@ -27,5 +27,6 @@ protected override DifficultyAttributes CreateDifficultyAttributes(IBeatmap beat
         protected override IEnumerable<DifficultyHitObject> CreateDifficultyHitObjects(IBeatmap beatmap, double clockRate) => [];
 
         protected override Skill[] CreateSkills(IBeatmap beatmap, Mod[] mods, double clockRate) => [];
+        protected override DifficultyAttributes CreateEmptyAttributes() => new DifficultyAttributes();
     }
 }

Templates/Rulesets/ruleset-scrolling-empty/osu.Game.Rulesets.EmptyScrolling/EmptyScrollingDifficultyCalculator.cs

@@ -27,5 +27,6 @@ protected override DifficultyAttributes CreateDifficultyAttributes(IBeatmap beat
         protected override IEnumerable<DifficultyHitObject> CreateDifficultyHitObjects(IBeatmap beatmap, double clockRate) => [];
 
         protected override Skill[] CreateSkills(IBeatmap beatmap, Mod[] mods, double clockRate) => [];
+        protected override DifficultyAttributes CreateEmptyAttributes() => new DifficultyAttributes();
     }
 }

Templates/Rulesets/ruleset-scrolling-example/osu.Game.Rulesets.Pippidon/PippidonDifficultyCalculator.cs

@@ -27,5 +27,6 @@ protected override DifficultyAttributes CreateDifficultyAttributes(IBeatmap beat
         protected override IEnumerable<DifficultyHitObject> CreateDifficultyHitObjects(IBeatmap beatmap, double clockRate) => [];
 
         protected override Skill[] CreateSkills(IBeatmap beatmap, Mod[] mods, double clockRate) => [];
+        protected override DifficultyAttributes CreateEmptyAttributes() => new DifficultyAttributes();
     }
 }