That's likely because it offloads most of the job to GPU. On a potato it's also very choppy, but CPU fans stays quiet indeed.
Gate's notes seems to put the most strain on CPU instead.
Seriously next level. I am on an old potato, and its smooth as silk, forward and backward. Backward. My potato is a ThinkPad i7 which slips into low speed at every single moment it can.
https://animejs.com/
It has way fancier animations and scrolls like butter