I could only manage 5 seconds. :-) The ball really moved fast on my machine. My cpu usage never went above 5%. Maybe your high cpu usage has something to do with the amount of video card( and/or ram) you have? I have a 2Ghz Athlon, 1 gig ram, and 128 meg Radeon video card.
You probably could incorparate a variable delay, selectable by the user. If I set the delay up to 40, it was more fun. Maybe you could test the system somehow, by seeing how fast the ball moves during a delay period, and automagically set the initial delay. Then have the delay decrease as the game goes on?
I'm not really a human, but I play one on earth.