RE: Odd Frame-rate behavior (Mac)
You tmlog seems fine. You've got to check your system for programs in the background, try disabling icloud, check for card overheating and test your graphics card with other graphics intensive games (the 6750M is not a strong card!), also try running from ac adapter and disable your laptop battery power save mode. Also run with 3D sceneries and not 4D sceneries, and disable extra features like smoke, clouds, trees etc.