The surprise isn't that the memory associated with `logIt` is leaked.

The surprise is that `logIt` holds on to the giant `str` object in its environment, despite the fact that there is literally no way for the `str` variable to ever be used again.

V8 is smart enough to not make `logIt` hold on to `str` if there are no closures at all which refer to `str`. It's the introduction of the unrelated `doSomethingWithStr` closure that forces `str` into the lexical environment.