While paused, the app prefetched the frames around the current one as soon as the viewer's
frame finished. During a drag every step changes the project, so those frames were stale at the
next step, and they held the CPU and GPU the next viewer frame needed: on the demo project a
drag step took 102 ms on average to show (up to 413 ms) though a frame renders in 20 ms. Paused
prefetch now waits until edits pause for 0.3 s: 16 ms a step (11 ms render).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>