The Other World Computing blog ran an experiment with the new Retina Macbook Pro:
Including the built-in Retina display, the new 2012 MacBook Pro 15″ can run four displays at their native resolution.
- Retina on laptop @ “best for Retina”
- iMac used as a display @ 2560 x 1440 via Thunderbolt
- iMac used as a display @ 2560 x 1440 via Thunderbolt/DisplayPort
- LG monitor @ 1920 x 1200 via HDMI
Moving images and media didn’t create any lag and we were able to play video on all four displays simultaneously.