Rust is closer to the metal than Go, so it's no surprise that it outperforms it. Actually I wouldn't at all be surprised if certain Rust applications could outperform certain C++ applications, based on the speed of libraries that are in use and how inefficient the code is written. While you can write inefficient code in any language, the reliance on some common libraries in C++ can work against it at times (for example, the std::regex library in C++ is fairly slow compared to other high-level languages).