Any CGA graphics mode tricks I should be aware of that could improve performance?
It's going to be a matter of the amount of memory to update every frame. So just do what everyone else does: shrink the size of the visible window and surround it with a border (or not). Faster machines get a larger window with reasonable frame rate, slower machines get a smaller window with reasonable frame rate. What would be cool is to be able to programmatically control the screen zoom on the HP 100LX/200LX.