diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index 588e448..81d27ae 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -3348,11 +3348,14 @@ public sealed class GameWindow : IDisposable
     /// velocity refinement is suppressed for a player remote. UMs are
     /// authoritative; the velocity fallback only fills the gap when retail
     /// does not send a fresh MoveToState (Shift toggle while direction key
-    /// held). 0.5 s is a defensible default — UPs arrive at ~5–10 Hz, so
-    /// a Shift toggle's first UP after the toggle is typically ~100–200 ms
-    /// after the most recent UM, well past the grace.
+    /// held). 200 ms covers the worst-case UM/UP race — UMs arrive on
+    /// direction-key events and UPs at 5–10 Hz, so the first UP after a
+    /// fresh UM lands ~100–200 ms behind. Tightened from 500 ms (commit
+    /// 8fa04af original) per user observation that the Shift-toggle
+    /// transition was visibly slower than retail; with 0.2 s the worst-case
+    /// added latency is just the UP cadence below it.
     /// </summary>
-    private const double UmGraceSeconds = 0.5;
+    private const double UmGraceSeconds = 0.2;
 
     /// <summary>
     /// Speed (m/s) above which a player-remote currently in WalkForward