Multi-Camera and Entity Hiding

How would I get an entity to only appear in one camera if more than one camera. That is to say, is there a way to hide entities from only certain cameras.

You could use a double render ... Note that renderworld will only render the scene from a camera which is not hidden. You can also use cameraproject mode, 0 instead ( iirc )

hideentity camera1
showentity camera2
showentity Entity1
renderworld()

hideentity camera2
showentity camera1
hideentity Entity1
renderworld()

The problem with a double render is that the thing that I want to hide is a tree and there happens to be a lot of trees and having the program decide which trees I want to hide and not hide (based on how far away they are from the camera) takes a lot of time and doing it every frame it slow.

Have you tried using EntityAutoFade then ?