I don't know, is it though? Properly done reference counting AFAIK requires using atomic increase/decrease in order to be safe, and that creates a bit of overhead every time you assign a reference, while assignment to a reference with a precise GC is basically a pointer assignment. It's much better for latency though, given that the overhead from rc is deterministic. It has been a few years though since I've looked into garbage collection techniques, so I could be a bit rusty about the current state of the art.
You only need atomic reference counting if you're sharing objects between multiple threads, but if you use an object from one thread at a time then non-atomic inc/dec is enough. Rust allows you to make the choice between the two kinds and the compiler can infer which kind you need to use.
Yeah - Rust can, because it also ensures you can't exchange data unsafely between threads, but C++ can't. That's why `std::shared_ptr` has to be thread-safe.