I'm running Vista x64 with SP1, and have a GeForce 7300GT using drivers 169.28.

Lately I've discovered that I get a huge frame rate drop if I switch LFS from full screen to windowed mode and back. The only solution to fix it was either to restart LFS, or go into Options/Misc and click the "Full screen vertical sync" a couple times so the LFS screen refreshes. Very annoying since I often switch to windowed mode to run the web browser or something.

After some testing and trying I've found an easier way to fix this. If you disable Aero while LFS is running, you can switch back and forth from full screen to windowed as many times you want without affecting the frame rate. All you need to do is right click your LFS icon, select Properties, go to the Compatibility tab and select the "Disable desktop composition" setting. See the image attachment.

Dunno if there's anyone else experiencing the same thing, if so I'd like to hear it so I know I'm not alone.

This is nice cause i switch screens alot... thanks dude

Huh. Can't say I've had the same problem here. Sounds like a driver issue to be honest. Have you tried updating your drivers?

Yep, was running the latest official drivers, 169.25. Then installed latest beta 169.28, with no difference. Even tried a fresh LFS install, same thing. It's weird, I reinstalled Vista a couple weeks ago, and can't say I noticed this problem before that.

make a virus chek and try older drivers

I decided to reinstall the OS - again... and so far, switching from full screen to window works just fine, with no fps loss. Thus not needing to turn off Aero as previously.