Magic..... just kiddin'.
A color laser has 4 DV units CYAN, MAGENTA, YELLOW and BLACK. For a full color print, it will send the paper through it's guts 4 times. This makes it kinda slow. In fact, mine (a QMS) is damn slow warming up too.
I just read about a Zerox unit that prints all colors in one pass thus making it just as fast printing color as blak and white.