When using the retina display of rMBP 13'' / 15'' at different resolutions than "best for retina", the resolution is internally doubled in each direction. The screen is rendered at that very high resolution before it is downscaled to fit the actual pixel count of the display. This is done to achieve a higher quality than when simply upscaling. Naturally, this puts additional pressure on the GPU and graphics memory. Thus, I would like to know whether it is possible with some 3rd party software to prevent this behaviour; i.e. if you can simply choose let's say 1680*1050 and have the screen rendered in this resolution and upscaled to fit the display resolution. If this was possible, I assume the UI would feel smoother at hopefully only little quality cost (which I am also interested in).