I just purchased a new monitor and plugged it to my 9600 GT. I used to play Civ 5 at max settings fairly smoothly, but now that I have 2 monitors to render at once, it's quite laggy. How could I focus the render power to the main display? Turning off the second one just won't do it.
I used to have an AutoHotkey script that I recorded of me opening the Display control panel, then disabling the second monitor. I didn't use it to redirect graphics power because I had two different graphics cards, but I had a program with a nasty glitch that froze up, created a memory leak eating all my RAM, stayed on top of all windows, and would not terminate if I had both monitors enabled.
So you could try going to the Display Control Panel and disabling the second monitor and see if that helps. If it does, you can make or find a script or program to disable or enable your monitor with one click.