Rust's compiler is not fast. At best it can beat C++ compilers - C++ being a language whose build times people love to bemoan - but usually it does far worse. This might change once rustc eventually gets proper incremental compilation (not the codegen-only thing that's currently in beta). Hopefully. Rust doesn't use header files, so in theory it should be possible to leapfrog C++ (at least until C++ gets modules standardized), but for now that's just theory.
Right now, I don't do much serious work in Rust, almost solely because of compilation speed.
Right now, I don't do much serious work in Rust, almost solely because of compilation speed.