It can be many things,
For sure, the huge amount of processes running under a factory installation is
enough to sluggish your experience. I've been able to reduce my memory usage to about
150mb after service disabling and msconfig.
If you happen to use a version older than painter 9, the program is slower, (being a mac application
tranfered on pc). In the IX version , corel has work with intel developpers, making the brushes run faster and take
much better usage of the processor.
You have to use use the newest drivers from wacom's penabled drivers and the additionnal file for newer tablet.
Turn Nvidia profiles off
I Work regulary with thoses two application at the same time with a 1.60ghz, 1.5 ram, 128mb video and it
works really well.
Hope it will help!