Another is amortization of bookkeeping: reference counting must be managed every time you record or remove a pointer while the GC does the tracing. So dependin

Another is amortization of bookkeeping: reference counting must be managed every time you record or remove a pointer while the GC does the tracing. So depending on your usage one may be faster than the other. Another is the opportunity to do the GC on another thread (careful!), or just when you have nothing else to do, meaning your hot path can be faster. Plus the very important case of circular or doubly linked structures that you mentioned.