Actually, I tested this out, ALL Windows act as real windows. So don't use windows at all.
I have nearly 200 dynamic objects (perhaps more) all with physics on. And last count of all objects was 275. True they use up a little memory, but well built maps can handel it.
And we come to well built maps. Did you know, that you should NEVER build in a strait line? This causes MASSIVE slowdowns. Build crooked, and build under (2 layers) but don't build strait.
Lights don't cause enough slowdowns to matter, except if you have terrible slowdowns already, but dynamic lights, those are problem makers.
Prefabs? No, those don't do anything. and have been known to cause problems.
I really should rebuild my map, but I have SOO many entitys placed, and soo many scripts attached, and soo many lights placed, and all of these settings everywhere that it would take 3 days to put it all back together.
And remeber, Doors and windows are leak centrals.
Merranvo, The Cool One
Anti-Noob Justice League, an ANJL of Mercy.