Does anyone know if there is a performance benefit to fullscreen opengl vs windowed opengl in OSX?

Question

The client for the MMO I work on uses two contexts, one for a window view and one fullscreen. I'm wondering if I just use a window sized to the display I can simply resize it if the user wants a smaller window so they can access their desktop.

Is their a performance penalty for running opengl in a window vs fullscreen assuming the same dimensions etc?

The client shell is written in cocoa; the game code itself is cross-platform.

We only support OSX 10.5 and 10.6 for the next release.

Answer 1

if there is a cost associated with clipping each frame, then yes.

Answer 2

Before 10.6, if your context did not have the full screen flag in it's creation, then you had a small performance difference. Now, with 10.6, this has changed.

Have a look at:

http://lists.apple.com/archives/Cocoa-dev/2009/Sep/msg01054.html