You could use Nim.

Yes, there are a lot of options, though it gets less mainstream pretty quick. Fortran, Ada/Spark, Ocaml, for a few other examples.

Those are not mainstream language, they probably lack libraries for most common use case, also most likely not as fast as Rust and probably even Go.

Right, which is why I said “gets less mainstream,” meaning that the examples listed were not mainstream. Apologies if that was unclear.

But you'd be wrong about your speed guesses. Ada/Spark and Fortran can be incredibly fast. Much of the world's fastest numerical code is written in Fortran, for example. (OCaml can be super quick too, though it can take a bit of care, and I get the feeling they've fallen behind in compiler tech in recent years.)