C++ also has async these days.

As for templates, I can't think of anything about them that would speed up things substantially wrt Rust aside from extern template and manually managing your instantiations in separate .cpp files. Since otherwise it's fundamentally the same problem - recompiling the same code over and over again because it's parametrized with different types every time.

Indeed, out of the box I would actually expect C++ to do worse because a C++ header template has potentially different environment in every translation unit in which that header is included, so without precompiled headers the compiler pretty much has to assume the worst...