Comment by amadeus

I probably didn’t explain this well enough, but your render times always have to be within the frame buffer (16.6ms for 60hz or 8.3ms for 120hz). Under normal circumstances even if you occasionally blow a frame buffer, with the over-scroll you won’t hit the sticky bounds.

The only time you will is if you’re scrolling at a rate where the jumps are quite large — large and fast enough typically where you’re not going to have a frame of reference for what you should see vs what you are seeing to notice you are behind.

Ultimately scrolling is managed on a separate thread from JS, which means if you do like an opt+click on the scroll bar, you’re going to make a jump that JavaScript can never keep up with, even if you’re under your frame times.

And with regards to safari, if your requestAnimationFrame is capped at 60hz but your scrolling is GPU composited at 120hz, this is the only way to keep scrolling at 120hz with 60hz dom updates and never see any blanking.