For NVIDIA Graphics Cards
- Open the Nvidia Control Panel. You can do this by right-clicking on the desktop
- Select Manage 3D Settings under 3D Settings
- Click on the "Program Settings" tab and select Generation Zero (or add its directory)
- From the second option "Select the preferred graphics processor for this program", select High-performance Nvidia processor from the drop down list (you can see what the automatic option is listed as global setting).
For ATI/AMD graphics cards
Open the control center in the same way as above. You may need to open graphics then PowerPlay and set plugged in and/or battery to maximise performance. You can also try going to graphics then 3D and move the slider to performance. Your computer may also have a switchable graphics tab where you can change the settings for individual programs.