It's down to hardware & driver support, I think.

The post doesn't work well at all on my Moto G, and I don't know why. The texture generation doesn't work right and the animation fails completely, and I haven't tried to debug it yet, because probably it's only that particular device that has whatever particular bug it is.

Works great on my machine: Firefox, Arch Linux, on-cpu graphics (i3-5020u)

Funny, it's smooth as butter in Firefox on my Nexus 5X.

Works at nearly 60 fps on my 50$ APU using Chrome on Linux.

WebGL crashes on Chrome on my Nexus 5 (2013).

Funny how that works.

Works like a charm in Safari on iOS and macOS.