Previous rAF interception fought with AC's painting-change monitor (which also schedules via rAF) — those callbacks queued behind p5's draw and produced the ~60-frame-then-stall artifact. Cleaner: after setup completes, call p5Instance.noLoop() to stop p5's internal requestAnimationFrame loop, then call redraw() from AC's paint hook. bios' requestFrame already gates the loop on the worker responding, so one redraw + blit per AC paint frame gives single-clock timing without touching global rAF.