Disable Aero which makes your GPU render BOTH your desktop and your game at the same time if you're in windowed mode (that's what I understand at least).  If you use fullscreen, don't bother because it automatically gets disabled if I'm correct in thinking that.  Also I think if you have your windows set to the classic or windows 98 or some other old look this won't make a major difference, but not sure about that. Navigate to "C:\Program Files (x86)\Steam\steamapps\team fortress 2" and find the "hl2.exe" Right click on it and go to "Properties" Under the "Compatibility" tab, select "Disable desktop composition" So essentially, use this with the launch options -windowed -noborder (throw in -novid too if you like to skip that valve video at start without pressing esc) and you'll be able to tab out just as the map changes or you connect to a server to do some internet browsing or something while tf2 is frozen up :D Here is an image to light the way if you have a little trouble.