It depends a lot on the coding style. The sort of Rust code that's heavy on Rc, Arc, Box, RefCell etc... (e.g. the typical band-aids to work around borrow checker restrictions) will be slower than typical C++ code (it's also possible to kill performance in C++ of course, just use std::shared_ptr for everything). E.g. I'd wager that performant Rust code is trickier to write than performant C++ code because you'll have to design your entire Rust codebase around borrow checker restrictions, while C++ lets you 'cheat' without having to fall back to helper types that incur runtime overhead.