Huh.... why would a CSS animation of a transform be slower than JS? This is strictly for the "CSS transform" case ofc - obviously pure webgl would be way faster.

I'm having a hard time seeing it. My experiments with CSS animation have always performed much better in CSS than JS (again, excluding it being pure webgl/canvas JS).

And ofc there's the nice bonus that it works if I haven't chosen to trust and whitelist their website for JS yet.