I have the complete OPPOSITE experience: the motion is jerky and inconsistent, like the seconds are struggling then catch up. (Firefox 74 on Windows 10 18363)
Concur. Since someone described it as 'beautiful and smooth' I opened it in Chrome.. beautiful and smooth (80% of the time). Since it's "just" SVG transforms perhaps this is a firefox:chrome difference (that said, I've built SVG transforms that run fine on both). It does invent the universe 31.25 times/second.. perhaps there's some JS optimizations we can do. [Update: basically smooth in IE11 too]