I wonder what’s wrong with Firefox? What is the bottleneck? The JavaScript engine? I’m guessing the thing is compiled to wasm anyway.
I would guess because the GPU world is messy and full of broken drivers full of hacks and workarounds, so it is rather a miracle that FF works so good, with the few engineers they have left.
(If you are on a chrome based browser, open chrome://gpu to get a glimpse into the work they have been doing just for your GPU and plattform)
While on native games the engine can workaround the driver issues, Web 3D APIs are at the mercy of the browser sandbox, where studios don't have access to possible workarounds due to lack of feedback on API performance.
Minimum specs: Memory: 4GB (8GB recommended)
The original ran on 128 MB or even less.