Eh.. I don't have an Intuos but the only time my graphire 4 will lag up my computer is either when I plug it in or there's been too much memory used from Photoshop.

Basically, the second I either restart the computer or close down photoshop, everything goes back to normal. It only happens for cases like a really large PDF file, I've left the computer on for a couple of days, I've left photoshop up for a while, or I plugged in my tablet while photoshop was already running.

Have you updated the intuos driver? When I plugged my graphire into the desktop computer (with Vista on it) it was like... ultimate lag show down until I downloaded the latest driver.