I'm not sure if this is a bug but when I switch to windowed mode Shift+F4 and then back to full screen mode my FPS nearly double. I verified this with FRAPS.

I'm using an old GeForce 6800 at 1920x1200 @2xFSAA. Latest drivers 169.21. I have Vsync turned on because I'm using an LCD.

Can anybody reproduce this? It would be interesting to know.

Just tried it on my 8800GTX - Slightly lower FPS in Windowed. No matter how much i try it it gets the same FPS in full screen when i switch.

In short - No i can't reproduce this.

Are you sure FSAA and VSync are still in effect once you switch to windowed mode and back? Because for me the fps stay exactly the same.

FSAA is still on and Vsync is still capping at 59.9FPS. I'm using an old 6800 GTS so maybe this is an issue they've fixed in newer hardware?

Quote from KirkH :

FSAA is still on and Vsync is still capping at 59.9FPS. I'm using an old 6800 GTS so maybe this is an issue they've fixed in newer hardware?

I'll try it with my 6800GT when I get a chance.

I'm using a 6600GT, so no, newer hardware is definitely not the fix

I've been window jumping in LFS since forever and never gained any FPS when full-screening back.

Your drivers are fubar, mate.

In another thread, looks like I'm not alone...

Quote from KROM :

This the case with me also.

Quote from wien :

I've seen a lot of people report the same thing. Must be a driver issue...

All I can think of it doing is it disabling AA and stuff.

I cant reproduce this either. When switching from fullscreen to windowed, i notice no loss/gain in FPS. Latest drivers on 2x 8800 ultras and o/c'ed Q6600.

It's very likely something is disabled upon maximizing, so it's not an actual gain, rather an increase you would get had you not had the particular option enabled. Interesting though, I wonder what's being disabled..

When you switch to windowed mode then the FSAA probably gets disabled and when you switch back it will stay disabled that could be the only thing that explains why you get more FPS that way

Also running on 1920x1200 the visual difference between no AA and 2xFSAA ain't that huge so you probably just missed the fact that FSAA is turned off

Nope doesn't work here; running 8800GT with oce'd 6420

No such magic with an 6800gt I'm afraid. As others said, it's probably disabling either AA or AF when returning to fullscreen.