“But it’s deterministic when the deallocations happen!” yeah I can see that clicking the red x made the app hang for 30 seconds, cool. In a generational GC I would have surely been mystified what caused the pause 10ms after I closed the document

(Actually I would expect that the garbage collection pass would bail out before long and reschedule the remaining work for the next pause, whereas ARC basically requires deallocation to occur now…)