Erlang, and hence Elixir, was never optimised for raw computation, it's all about the massive concurrency (we can handle literally millions of processes), fault

Erlang, and hence Elixir, was never optimised for raw computation, it's all about the massive concurrency (we can handle literally millions of processes), fault-tolerance and scalability. This is not surprising as no language is good at everything, you have to pick and choose what you is most important. In most systems different parts will have different requirements so I think it is perfectly reasonable to use multiple languages in a system. Erlang is very good at communicating with other languages/systems.