First off, I own Unity Pro.
I've been looking in to occluding lights when they aren't being viewed for a while now to improve performance. The main methods I ran in to were using BecameVisible() and testing the camera fulcrum.
My main problem was that if the player is viewing an area that would be lit by the light, I still want the light to be on.
Currently I'm using a method which checks to see if the lit area is in the camera fulcrum, but the problem is sometimes lights are in the fulcrum without actually being visible by the player (e.g. a wall between them and the player). I've tried raycasting to them but you can never get detailed enough for the actual lit area (the best I could figure was using renderer.bounds.extent and renderer.bounds.center to calculate the maximum lit points from the light).
Does anyone know of an easy way in Unity Pro to occlude lights? Or could you tell me a good way to use that camera fulcrum method I was talking about?