Well, it sounds like that's what you should do to me. If there's a swinging blade (xscreensaver) and you want to dodge between it (beep) you have to have better time resolution than the period of the pendulum. Maybe you could increase the resolution only near the time when the screensaver should be kicking in? Then, for the majority of the time, you can be less of a cpu hog. That would still leave you vulnerable to anything else that might be going on in your system that also has a high resolution.