> Doesn't seem like that would be something inherent to ref counting. It is inherently so. A reference count is an atomic mutable value that must be updatable

> Doesn't seem like that would be something inherent to ref counting. It is inherently so. A reference count is an atomic mutable value that must be updatable by any thread. A significant selling point of ARC compared to traditional ObjC reference counting was that the compiler could elide retain/release calls better than the programmer could, thus preventing a ton of stalls.