diff --git a/public/js/webgl-book-lab.js b/public/js/webgl-book-lab.js
index 054ada7..a46272c 100644
--- a/public/js/webgl-book-lab.js
+++ b/public/js/webgl-book-lab.js
@@ -2221,7 +2221,11 @@ function handlePageTextureRecords(event) {
     if (!detail.right && effectivePageMeta.right?.kind === 'blank') {
         applyExplicitBlankPageTexture('right', effectivePageMeta.right, 'page-texture-records');
     }
-    markStaticSceneBuffersDirty();
+    // A page-texture content change moves no geometry, so it must NOT force the AO/shadow/
+    // reflection recompute (that produced 23-42ms frames on every block during playback).
+    // AO and shadows depend only on geometry; the soft tabletop reflection picks up the new
+    // page on its normal throttled cadence. Only geometry changes (flips, camera, rebuild,
+    // resize) dirty the static buffers.
     document.documentElement.dataset.webglPageTextureMetrics = JSON.stringify({
         width: leftCanvas.width,
         height: leftCanvas.height,