For reference my numbers are for an RTX 4070, Firefox has no excuse for not being able to crack 60 fps on a demo that looks like it's from the late 2000s in terms of graphics.
> 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...