Optimise Windows 8 for Cubase 7

I just upgraded from Cubase 5 and Vista to Cubase 7 and WIN8 Pro, using a Dell PC, 4ghz ram, 2.66ghz dual core processor. WIN8 alone runs great, but it appears that the combo is too much for my avg. PC, so I am shopping for a new one with some serious horsepower. My old setup ran perfectly, but using WIN8, Cubase 7 sputters on playback and freezes/crashes when I add any effects. I closed down all active apps in WIN8 to reduce demand, changed settings, etc., but no luck. I’ve used Cubase successfully for many years and look forward to getting my studio running again.