[Amadou]

Part of that is due to having a hardware mouse cursor. Basically all the interrupt handler has to do is load the new coordinates into some registers on the video co-processor and co-processor takes care of all of the work of blitting the mouse around the screen. It makes processing the mouse interrupts very light-weight.

[snom380]

Which OS and hardware platform are you referring to now?

[makomk]

I think this applies to most desktop OSes and nearly all the hardware platforms they run on, aside from virtualised ones.