I've been using the latest SDL 1.3 with OpenGL to develop a game that is now in beta testing. Some users are reporting massive slowdowns when fullscreen -- about 18fps -- on something that can easily run 200-300fps in windowed mode. These same users are usually able to "fix" the problem by toggling between windowed and fullscreen modes once or twice. It then runs full-speed for them even fullscreen.
I'm unable to duplicate it on any of the systems I test on. And the three users who are experiencing the slowdown are on a range of different systems (all do happen to be Intel Dual Core 2 systems) running different graphics cards, so I doubt it's a driver issue.
What's encouraging is that the problem is demonstrated even in SDL's very minimal testgl2 demo that comes with SDL. If you simply modify the demo to run fullscreen, it'll demonstrate the same slowdown when fullscreen, as long as it's run on one of the "affected" systems. I'm curious if anyone here has MacOS X systems that duplicate the problem. To see, just download the latest SDL 1.3:
http://www.libsdl.org/tmp/SDL-1.3.zip
and build the SDL framework and then the SDL Test, compiling the gltest2 demo. Open up gltest2.c and put:
SDL_SetWindowFullscreen( state->windows[0], true );
right before /* Main render loop */
If you CAN duplicate the problem on your system [i.e. it runs under 60fps when fullscreen -- check your console output for the frame rate when you quit), please post here. Especially if you think you might have ideas for how to fix it! I've been trying to fix this for a couple of weeks now, and have scoured the internet to no avail.
