Fixed VR Frame Interpolation frame-history copying bottleneck

OPENXR.md

@@ -252,6 +252,12 @@ produced 359 new stereo submissions in 4 seconds (89.7 FPS). This verifies submi
 not full-race performance or visual quality on a headset. Pass a draw count, for example
 `stereo_frame_worker_smoke 2000`, to stress uniform preparation and renderer/producer overlap;
 `stereo_frame_worker_smoke 2000 0` checks native stereo with interpolation Off.
+Use `stereo_frame_worker_smoke 1000 1 1` to exercise ten-matrix palettes and their
+larger uniform history, or `stereo_frame_worker_smoke 1000 2 1` to switch interpolation
+On/Off during recording. The test compositor discards obsolete ticks and uses
+high-resolution waits on Windows, keeping missed ticks from accumulating into bursts.
+It pre-warms the next game frame like the runtime and excludes the first 60 frames
+from timing so shader compilation and initial resource allocation do not skew steady-state results.
 The test checks that the producer stays above 55 FPS as well as checking headset submissions;
 replaying an old scene more often must not hide a slowed simulation. Validate actual races in VDXR at 90 Hz with
 Auto/90 selected, including race entry/exit, first person, recentering and pauses.
@@ -263,6 +269,11 @@ Retained interpolation reserves eye ranges at seal time and fills them once at t
 time. VR interpolation also releases the producer after sealing so eye encoding can overlap the
 next game frame, as it does with desktop interpolation.
 
+When VR interpolation is enabled at batch start, uniform recording also uses cached CPU
+memory. Matching and history capture read that buffer, then the used prefix is copied to
+the mapped upload buffer before unmapping. The backing choice stays fixed until the batch
+ends, including mid-frame flushes, so live setting changes cannot invalidate pending tasks.
+
 ## Current limitations
 
 - Only the project's supported PAL `RMCP01` translation has race instrumentation addresses.