1. I do not think this is possible. In fact, I don't think it is possible at all. To not return time slices to any other apps running on the machine? I doubt it.
2. Try it and find out. Would be an easy thing to try. Draw 2000 images on screen check speed. Then draw 1000 on screen and 1000 off screen, check speed. Then just draw 1000 on screen, check speed.
2. Try it and find out. Would be an easy thing to try. Draw 2000 images on screen check speed. Then draw 1000 on screen and 1000 off screen, check speed. Then just draw 1000 on screen, check speed.