diff --git a/docs/ISSUES.md b/docs/ISSUES.md
index 274a5457..34a46c70 100644
--- a/docs/ISSUES.md
+++ b/docs/ISSUES.md
@@ -55,6 +55,23 @@ builds off the critical path (23 s → 0.2 s) and is quality-neutral
 preserved; a pool of 1 reproduces the old serial behavior,
 regression-tested in `LandblockStreamerPoolTests`).
 
+**Lead-review refinement (2026-08-17, same day):** the identical ~31 ms
+period across BOTH configurations is unlikely to be a coincidence of two
+different limiters — the sharper hypothesis is that ONE ADMITTED
+LANDBLOCK'S update-thread publication itself costs ~31 ms (GPU upload +
+registration + typed-budget accounting as one indivisible admission).
+The 2 ms `MaxUpdateMilliseconds` floor guarantees exactly one admission
+per frame; that admission stretches the frame to ~31 ms; the hold
+therefore runs at ~32 fps and 1 admission/frame × 32 fps = the measured
+flat 32/s — in the OLD binary the serial builder happened to produce at
+the same ~31 ms/block, which masked the admission cost entirely. This
+predicts: (a) tunnel frame time during the hold is ~31 ms (measurable
+from the existing frame profiler), and (b) the fix is splitting or
+off-threading the per-landblock publication cost — NOT raising budgets
+(already disproved twice). `MaxCompletionsPerFrame = 4` (the quality
+line) is a profile SCALE of the same env-tunable options, so it is also
+already exonerated. Verify (a) first next session.
+
 ## #417 — World ambience keeps playing (and re-firing) on the character-select screen after the in-world logoff
 
 **Status:** ✅ FIXED 2026-08-17 (logout-audio round; fix + tests in the same