Constant UI responsiveness

The application uses FreeType to display anti-aliased text, but without any special optimization techniques other than brute caching and double-buffering. It works well, but can't afford to do much more without more complex optimization techniques (and then the best way would probably be to start using X).

The target machines range from Geodes with the power equivalent of a Pentium MMX@266MHz to modern Celerons @2GHz, so it's bearable enough on the Geode and instant on the Celeron.

I also can't afford to optimize the code for a specific machine, so it's just compiled with generic optimizations.

This POS machines are not always well tested. They are made to be compact and sometimes they don't have enough cooling space. For eye candy we have a screen-saver using alpha-blending to show a flashlight passing on the screen. Some lower end machines lock solid because they heat too much, so we limit that screen-saver to no more than a 5-minutes run.