Is there anyway to see why ScreenUpdating is taking so long?

I turn off ScreenUpdating at the beginning of all Events, and turn it back on when it's done.

I have managed to determine that when ScreenUpdating is set True that it takes longer than I like.
I know that turning it on automatically triggers a calculation, which I assume is the reason it takes longer than necessary.
Is there any way to determine what is being calculated? And more specifically how long each formula is taking?

I'm guessing that turning ScreenUpdating to True and back to False while the macro is running would not help when the macro ends. Is that right?

BYW: I've seen several people say that ScreenUpdating automatically gets set True when the macro ends, but the help file says that it doesn't.