Third, Marcel Weiher explains Apple’s obsession about keeping memory consumption under control from his time at Apple as well as the benefits of reference counting:

>where Apple might have been “focused” on performance for the last 15 years or so, they have been completely anal about memory consumption. When I was there, we were fixing 32 byte memory leaks. Leaks that happened once. So not an ongoing consumption of 32 bytes again and again, but a one-time leak of 32 bytes.

>The benefit of sticking to RC is much-reduced memory consumption. It turns out that for a tracing GC to achieve performance comparable with manual allocation, it needs several times the memory (different studies find different overheads, but at least 4x is a conservative lower bound). While I haven’t seen a study comparing RC, my personal experience is that the overhead is much lower, much more predictable, and can usually be driven down with little additional effort if needed.