> The performance side of things I think is still up in the air because ARC certainly does introduce overhead.
As you said, they can both introduce overhead, but the ARC overhead is way worse. Really the only reason to use garbage collection (which is really complex) over ARC (which is simple) is the performance and control you get. Otherwise it would not be worth the implementation cost. The question is not “up in the air” on performance; production-grade GC’s are a clear winner. I would even be doubtful that CoW could make up the difference. But I would be interested to see data suggesting otherwise.
> The performance side of things I think is still up in the air because ARC certainly does introduce overhead.
As you said, they can both introduce overhead, but the ARC overhead is way worse. Really the only reason to use garbage collection (which is really complex) over ARC (which is simple) is the performance and control you get. Otherwise it would not be worth the implementation cost. The question is not “up in the air” on performance; production-grade GC’s are a clear winner. I would even be doubtful that CoW could make up the difference. But I would be interested to see data suggesting otherwise.