> I think I read that too, but I am not sure that this is actually true. Please correct me if I am wrong, according to the Rust developers code generation seems to be the bottleneck.

You're both right. The problem of C++ is how '#include' works, that it just includes the content of all files and therefore there's more overhead on the lexing side.

Rust's "equivalent" of '#include' is 'use', which doesn't have this problem, because it doesn't concatenates files.