2 ms·
Firefox 58, 60FPS.
Chrome: 40 FPS
Firefox 58, 60FPS.
Chrome: 40 FPS
I get a steady 60FPS in both FF 56 and Chrome 61/62.
It would probably be useful to include hardware.
60 FPS in Firefox 57.0, Chrome 62.0.3202.89, and Safari 11.0.1, on a 2017 iMac running High Sierra (10.13.1) with a 3.4 GHz Intel Core i5 and a Radeon Pro 570 4 GB.