There are still some things that C++ can do that Rust can't. A few of the larger and common examples would be, specialization, placement and variadic generics.
At least variadic generics isn't really a performance thing, it's just an example of a rough edge you run into here and there. Specialization and placement can be pretty important for performance though!
I was asking in the context of OPs claim. And that was regarding low level optimizations. I think only placement is a valid counterexample here but AFAIK there is support for Rust in that, if a bit elaborate in expression.
At least variadic generics isn't really a performance thing, it's just an example of a rough edge you run into here and there. Specialization and placement can be pretty important for performance though!