bottleneck graphics card?

hello : )

I have quite a large patch with audio ins/outs delays , 0 n 1 processing some vst inserts and OSC messaging.

ive just tested this patch on my main machine.When I zoom out to look at this patch as a whole, it is very sluggish in response. in fact some times when I zoom out it freezes. :( i monitor my ram (@ 1066mhz)

ram available before i open the patch = 1711mb
ram after i open the patch = 1460mb

So the ram seems o.k.

I monitor the cpu (quad @ 1600 fsb 2.8 x4 ghz)

The cpu load when the patch dsp is enabled on ( and i'm zoomed in) = 3 %
the cpu load when the patch dsp is enabled on (and im zoomed out) = 23% (mainly on core 3 but also 2 and 4)

So the cpu seems fine also but i stil get the sluggishness and freezes. As I am not really an expert, I would say i need to invest in a new graphics card? I ask because, maybe there is something i am overlooking? A setting to reduce the load on the graphics side of things??

my card has Clock Speed: 525 MHz RAMDAC Clock Speed: 400 MHz , 256mb ddr2. (asus eah2400pro) real cheap thing 25 uk pounds or near about !

what graphics cards do you guys run on your big patches?

thanks for any help. : P