That's not normal. In my system, which is a mac, it goes the other way around. I have a good performance on Logic, but I feel that Live is somewhat lighter on the system. What I think you should do is contact your soundcard's manufacturer with as much detailed info as you can, as I'm sure you won't be the only one with those problems. They may even have some step-guide to fix it - worth giving a shot I guess.
But all in all, Diva is one heck of a cpu eater.
