cosmove I think you may have misread my response. I'm trying to state that the vertical sync is this problem. I can play 7680x1080 across 4 projectors and maintain a high frame rate. 70fps. When I enable vertical sync depending on the amount of outputs I enable, it reduces the framerate.
1 output = 60fps
2 outputs = 40fps
3 outputs 20fps
however with with vertical sync disabled I can maintain a high frame rate. 70fps
I'm suggesting that the same could be happing to timdas, since he's using a slower video card is why he stuck at 4 fps.