Hey guys, Whenever I go to play D3 in windowed I always seem to get lag, when I play fullscreen its fine but I would rather play windowed fullscreen so when I alt tab its a lot faster. Just wondering if there is anything I can do to speed it up? added some extra RAM today as well but nothing.
Playing a game in windowed will always produce a laggier experience than having it in fullscreen. It's caused by your video card having to calculate which parts of the window are actually being displayed on your monitor, and which have been dragged off the screen by window movement. Besides that, it also has to render the parts of your desktop that are still visible (your taskbar, I'm assuming), and render the game in an unusual format because of the borders, whereas fullscreen allows it to just use a standard monitor size to render (i.e. Fullscreen: 1920x1080, windowed-full: 1900x1045 or something like that, so it has to resize everything being rendered to fit the window).
I usually don't see any meaningful performance hit when running games in Windowed mode. And I always use Windowed mode. Have you tried closing your browser to make sure it's not Flash player that's causing this?