From the SU10 Beta Release Notes:
- Low power mode is now available for PC users via the Experimental option menu in game. While in the menu, this option now displays a blurred image instead of the hangar in the background. Other options and behaviors are available to reduce the sim’s power consumption: you can enable VSync, framerate is limited to 20FPS when you minimize the window, and it’s divided by 2 when you launch a download
Here is where the option exists now in the SU10 Beta:
