Is there an option in steam to disable the 2nd monitor when you run the game? I'm using my job's PC during lunch break but i don't want to disable the 2nd monitor each time i boot civ.

With dual monitor and my current setting, the game is somewhat playable, but i have to drop all the settings to low and it's still lagging a bit.

Put the game in windowed mode and change the resolution to fit in one of your screens.

I fear it won't change a thing. I'll try it, but i'm not sure. The problem is that the video card still had to draw to 2 full screens instead of focusing on just one.