Comment by nu11ptr

Only when used in a naïve way, which Rust does not. For example, the increments/decrements are done only when "clone" is called and scope exit respectively, and based on Rust ownership/borrow checking, is rarely done combining the best of both worlds (but yes, implementations with aggressive increment/decrements in loops and on every function call can be very slow). Rust also separates Arc (atomic refs) and Rc (non-atomic refs) and enforces usage scenarios in the type checker giving you cheap Rc in single threaded scenarios. Reference counting when done in a smart way works pretty well, but you obviously have to be a little careful of cycles (which in my experience are pretty rare and fairly obvious when you have such a data type).