Fascinating stuff. It's so weird to realize that such a critical piece of code is still changing significantly after 10 years at NeXT and 10 years at Apple.
I think it's weirder that so often such critical bits still are the makeshift unoptimized first version. But I know how it works in the real world, it's good enough and there are no reported bugs, so don't touch it until you have implemented all these features and fixed all these issues....
