C++'s experience has caused Rust to rightfully learn the lesson that you don't allow optimizations to change the semantics of the program like that. Rust's goal is to be fast enough that any performance difference between C or C++ is too negligible to bother considering, and it's achieved that. It's not going to sacrifice reliability on the altar just to make up a measly 3% gap. There are plenty of ways that Rust's stricter semantics allow it to produce faster code than C++ (no move constructors or implicit copy constructors, thorough reference aliasing information, automatic generic struct layout optimizations, safe non-atomic refcounting, safe concurrent stack references, less defensive copying, etc.), it does not need to "convince C++ language people" of anything.