Nvidia Screen Position Bug?

I have a 480 with 260.19.12 drivers installed on 64 bit OpenSUSE. I have two monitors and I’m running my application in windowed mode. I noticed there is one window position that causes my application to run at 70 ms per frame. If I move the window a few pixels, then the framerate speeds up 10 fold to 7 ms. Has anyone else seen anything like this?