Does this printer connect to your computer by USB or parallel port? How much memory does the printer have, i.e. of it's own memory? What make and model printer is it?
I have two Canon printers attached to my computer, models BJC-2000 and BJC-3000. The BJC-2000 is a parallel port device and, just as in your case, my CPU usage jumps to 100% when I print with it and other tasks on my computer become noticably slower. The BJC-3000 can use either parallel port or USB; I have it connected via USB. When printing with it, CPU usage increases, of course, but does not shoot all the way to 100% and the impact on computer performance may not be noticeable at all unless a very large document is being printed.
If that printer can use a USB port, try that. If not, assuming you've got the best driver for your printer installed, the only solution, I believe, is to get a new(er) printer.
