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

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

A very neat walkthrough of how to write a particle simulator in javascript, starting from the simple, and moving to the more complex.

Along the way, the author profiles to remove bottlenecks and tries out new ideas.

Also they have an idiosyncratic writing style, I found it endearing.