I've been kinda wondering that too. I don't think invisible stuff does, at least you would think that it wouldn't... but then again, one of the best ways to optimize your games in MMF was to make off-screen stuff invisible. Yeah, stuff that's not even on the screen
. Makes no sense at all but it actually works.
And yeah, I know Rich just answered before I could post but dammit, I spent the time to type it out so I'm posting it