[the_duke]

It's especially bad with the CSS frameworks that people slap on their sites.

Various Material UI implementations are notorious here because they have fancy animations everywhere.

[hknd]

^ this!

I've seen so many jquery libraries used on sites to get a quick fancy animation, but then it used something like: setTimeout(() => { element.height += 2; }, 50)

Which literally brings a 60+fps page to <5fps on a high-end machine.