Full screen rendering would be a lot slower. As it is, I get 19 fps in color and 36 fps in black and white. The program draws a filled rectangle for the sky, then draws 540 vertical lines on top of that for the earth color, and then 540 lines on top of that for the surface. Full screen rendering (1024x768) would require about twice as many lines in either mode, so it would be about half as fast, and probably less than that, because the rectangle would be larger and the earth-coloring lines would be longer.