At the same time Rust forbids some practices pushing a coder to choose another path. To name a specific example, try to roll out your own dynamically sized type type or a self-referential one. Such small things could contribute to performance too.
Yes, there are definitely things one may do in C++ that aren't possible in Rust. In the absence of bugs, I think you could pretty much recreate any Rust program in C++ and have it be just as fast.
Of course, you can't assume the absence of bugs in real world software. The C++ version would lack any of the safety added by Rust's compile time checks.
