Last time I checked (which was a few years ago), the performance gain of porting a non-trivial calculation-heavy piece of code from Python to OCaml was actually 25x. I believe that performance of Python has improved quite a lot since then (as has OCaml's), but I doubt it's sufficient to erase this difference.

And OCaml (which offers a productivity comparable to Python) is sensibly slower than Rust or C++.