This is so much fun; particular props for making everything forkable in codesandbox:

https://dgerrells.com/blog/how-fast-is-javascript-simulating-20-000-000-particles

How fast is javascript? Simulating 20,000,000 particles

The challenge, simulate 1,000,000 particles in plain javascript at 60 fps on a phone using only the cpu. Let’s go.

David Gerrells