We’re not implementing in Rust but taking an existing piece of middleware (Bullet) and using it. Performance wise it’d be an apples to oranges comparison but our general understanding from benchmarks, our own personal experiments and blogs like the one you posted there is not to expect miracles but more consistency and less footguns (e.g. megamorphic behaviour).

This is another good summary: https://ianjk.com/webassembly-vs-javascript/

I would say there is hope when SIMD is supported across major browsers if your workload will make use of it. Just waiting on Safari. And there might well be more performance to eek out of the JIT compilation.