Laggy extended desktop performance?

[DrewSG3]

I upgraded a few months ago to a AMD HD6950, and a Panasonic 50" ST50 plasma TV, when in extended desktop mode, both monitors are pretty laggy. If I use each display separately, performance is normal. I never had this problem before when I had my old setup of an HD4850 and Phillips 42" LCD HDTV.

Does anyone know what could be wrong?

 

[KingFatty]

Try connecting the monitors to a different combination of ports on the video card.