thanks for your thoughts as well! Here's the article from anandtech that explains how scaling works on the retina macbook: http://www.anandtech.com/show/6023/the-nextgen-macbook-pro-with-retina-display-review/6
"If you select the 1680 x 1050 or 1920 x 1200 scaling modes, Apple actually renders the desktop at 2x the selected resolution (3360 x 2100 or 3840 x 2400, respectively), scales up the text and UI elements accordingly so they aren’t super tiny (backing scale factor = 2.0), and downscales the final image to fit on the 2880 x 1800 panel. The end result is you get a 3360 x 2100 desktop, with text and UI elements the size they would be on a 1680 x 1050 desktop, all without sacrificing much sharpness/crispness thanks to the massive supersampling. The resulting image isn’t as perfect as it would be at the default setting because you have to perform a floating point filter down to 2880 x 1800, but it’s still incredibly good."
When mapping the cube on stage, I had a projector with 1024x768 resolution, the movies and stills were not larger than that. In the first scene there is a picture of a bird mapped on one side of the cube, the next scene has a video in it which is attached to 3 cornerpin projector as it is mapped on 2 sides of the cube, plus the back wall of the stage. so there is one movie and one still photo playing when transitioning between the two scenes. I'm sure the resolution of than picture plus the movies could even be reduced, given a total resolution of 1024x768, but I don't think this is the problem..
I haven't worked on this show for a couple of weeks now and will experiment a little with it as soon as I can.
Thanks for your insight, I'll try different resolutions and target fps!