There's nothing inherently slow about the way you structure a program in Erlang. Most of the problems come from copying values around when sending them across processes.
Erlang/BEAM is significantly slower than either Go or Rust. Its speed reputation was often misunderstood; it was very good at juggling green threads, but it was never a fast programming language. Now that its skill at juggling green threads is commoditized, what's left is the "not very fast programming language".
It's not the slowest language either; it has a decent performance advantage over most of the dynamic scripting languages. But it is quite distinctly slower than Go, let alone Rust.
