To elaborate on the 2nd part: idiomatic Rust is usually slower than the absolute fastest program you could have written. Making sure you are not allocating (usually wrt to Strings and Vecs) in the hot path often takes a non trivial amount of work compared to naive solution (for ex, fighting with borrow checker instead of cloning, or or allocating your Vecs and passing results thru a mut ref parameter vs a return value) and also makes your code uglier.

That said, writing an ultra performance program in Rust is easier than using any other language in existence rn.