For what its worth, when I monitor my systems (I run on 3 custom built workstations) my P2200 Quadro gpu lays dormant on all pixnub plugins that I use.
On the other hand, my Processor is pegged at max speeds.
My point is that your gpu may not be what needs upgrading.
I would look into upgrading the processor, or atleast monitor performance in task manager when attempting to run pixnub.
Hope that helps. Good luck!