I believe so, as cargo defaults to the number of cores, as per this issue: https://github.com/rust-lang/cargo/issues/2805

For what it's worth, this guy noticed a nearly 2x speedup in compiling OpenSSL, which is C code, so I assume GCC or Clang: https://twitter.com/sandofsky/status/1331732592958214145

This suggests, though it does not prove, that the performance improvement for code compilation is likely not exclusive to a single language.