fps on different instances

Hi,
I am having this issue when running multiple wow clients.
The clients I am not playing on have their fps dropped to 8, not higher, not lower, and the client I currently play on will always have is fps maxed, which is capped on 45.
It seems just whatever client I am not playing on have their fps capped to 8 for some reason I cant figure out, anyone experienced the same thing.
I am petty sure my video card(ati hd 4870) should easily handle multiple clients with high fps.

/console maxfps XX
/console maxfpsbk XX

Where XX is a number of fps. sounds like you used an app at some point that set these to 8 and 45. The bk one is background as in when that wow window is not the focus window.

Does it occur in Azjol-Nerub instances? Or any other large out door area instances?

A good chunk of the graphics actually gets done by the cpu and not the graphics card.