There is a trick in truly exclusive references (marked noalias in LLVM). C++ doesn't even have the lesser form of C restrict pointers. However, a truly performance focused C or C++ library would tweak the code to get the desired optimizations one way or another.
A more nebulous Rust perf thing is ability rely on the compiler to check lifetimes and immutability/exclusivity of pointers. This allows using fine-grained multithreading, even with 3rd party code, without the worry it's going to cause heisenbugs. It allows library APIs to work with temporary complex references that would be footguns otherwise (e.g. prefer string_view instead of string. Don't copy inputs defensively, because it's known they can't be mutated or freed even by a broken caller).
And they're all extremely buggy, to the point where Rust has disabled it and reenabled it and disabled it and so on many times over as bugs are constantly discovered in LLVM because Rust is the only major user of it
A more nebulous Rust perf thing is ability rely on the compiler to check lifetimes and immutability/exclusivity of pointers. This allows using fine-grained multithreading, even with 3rd party code, without the worry it's going to cause heisenbugs. It allows library APIs to work with temporary complex references that would be footguns otherwise (e.g. prefer string_view instead of string. Don't copy inputs defensively, because it's known they can't be mutated or freed even by a broken caller).