With std::shared_ptr each copy has a pointer to the ref count & there is only one ref count, atomically updated with a cmpxchg instruction. Not sure what you me

With std::shared_ptr each copy has a pointer to the ref count & there is only one ref count, atomically updated with a cmpxchg instruction. Not sure what you mean by "references are updated or moved around"? But I agree that GC has higher thruput than malloc/free as most gc allocations are a single op, at the cost of higher initial memory usage and worst-case latency. That's why "scripting" languages like python / perl use refcounting as they need to start quickly and might not run for very long, whereas java / c# programs tend to be longer running.