I ran some of these in comparison with Chrome, and Chrome was consistently faster, but only marginally (1-20%). I'm actually quite impressed, an integrated Intel HD 620 / 4x2.4 GHz (!) rendering 10,000 fishes at 30 FPS in a webbrowser.
> on a demo that looks like it's from the late 2000
The literal visual aesthetics aren't really important for the test. You could place some nicer shaders and it wouldn't necessarily change the compute load. Hell, it could just be highly unoptimized. Benchmarks are mostly about having something static to test, not making something visually pleasing.
But no it's not capped at 30, it jumps to like 33, 34 sometimes with those settings, it's capped to 60 like Chrome as well. Probably vsync.
[0]https://developer.mozilla.org/en-US/docs/Web/API/Window/requ...