There's also a project to add a static JS compiler, but it's been in development hell for the last 3 years: https://github.com/facebook/hermes/tree/static_h
They increased the interpreter performance by quite a bit, but JITs are impossible on iOS, so it can never be fast.
We have a RN app that needs to do a lot of geometry processing and things like polyclip are unbearably slow, so we had to add native modules to accelerate them. The web version with a true JIT works just fine.