[pulse7]

With optimized RC (which deffer deallocation) you have no "constant-time performance guarantee", because you don't know at which time the deffered deallocation will happen... And all modern RC implementations are heavily optimized - especially in Apple's ecosystem...

[camgunz]

Yeah I think generally what people mean here is, "if I'm aware that freeing objects takes time, I expect to spend that time when I free the objects, not at some undetermined point in the future". That's not the case if you do any kind of deferring, at which point you're pretty close to a "classic" GC system.