From f4199958d93995b0db1235fc986e1f07d1ef80ec Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Thu, 26 Aug 2021 04:01:37 +0900
Subject: [PATCH] Avoid unnecessary array/LINQ operations when replay frames
 have no action changes

---
 osu.Game/Input/Handlers/ReplayInputHandler.cs | 21 ++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/osu.Game/Input/Handlers/ReplayInputHandler.cs b/osu.Game/Input/Handlers/ReplayInputHandler.cs
index cd76000f98..e4aec4edac 100644
--- a/osu.Game/Input/Handlers/ReplayInputHandler.cs
+++ b/osu.Game/Input/Handlers/ReplayInputHandler.cs
@@ -42,9 +42,24 @@ public void Apply(InputState state, IInputStateChangeHandler handler)
                 if (!(state is RulesetInputManagerInputState<T> inputState))
                     throw new InvalidOperationException($"{nameof(ReplayState<T>)} should only be applied to a {nameof(RulesetInputManagerInputState<T>)}");
 
-                var lastPressed = inputState.LastReplayState?.PressedActions ?? new List<T>();
-                var released = lastPressed.Except(PressedActions).ToArray();
-                var pressed = PressedActions.Except(lastPressed).ToArray();
+                T[] released = Array.Empty<T>();
+                T[] pressed = Array.Empty<T>();
+
+                var lastPressed = inputState.LastReplayState?.PressedActions;
+
+                if (lastPressed == null || lastPressed.Count == 0)
+                {
+                    pressed = PressedActions.ToArray();
+                }
+                else if (PressedActions.Count == 0)
+                {
+                    released = lastPressed.ToArray();
+                }
+                else if (!lastPressed.SequenceEqual(PressedActions))
+                {
+                    released = lastPressed.Except(PressedActions).ToArray();
+                    pressed = PressedActions.Except(lastPressed).ToArray();
+                }
 
                 inputState.LastReplayState = this;