See it for yourself — live
The same seeded scene, same body count, same fixed 1/60 s
step — run across Fast2D and the popular JavaScript 2D physics engines in
your browser. Every engine runs at its own out-of-the-box default
settings with sleeping off, so you're watching the real steady-state cost a
developer actually gets. Lower ms/step is better.
Identical seeded scenes and timestep for every engine. Some engines run in their own unit space (converted back for drawing), so fall speed can differ slightly — the measured ms/step is what's compared.