Comment by MaulingMonkey

> Is it?

Yes.

> What happens if you remove that one last reference to a long chain of objects?

A mass free sometime vaguely in future based on the GC's whims and knobs and tuning, when doing non-refcounting garbage collection.

A mass free there and then, when refcounting. Which might still cause problems - but they are at least deterministic problems. Problems that will show up in ≈any profiler exactly where the last reference was lost, which you can then choose to e.g. ameliorate (at least when you have source access) by choosing a more appropriate allocator. Or deferring cleanup over several frames, if that's what you're into. Or eating the pause for less cache thrashing and higher throughput. Or mixing strategies depending on application context (game (un)loading screen probably prioritizes throughput, streaming mid-gameplay probably prioritizes framerate...)

> You might unexpectedly be doing a ton of freeing and have a long pause. And free itself can be expensive.

Much more rarely than GC pauses cause problems IME.