Quartz Builder movie framedrops

Hey My composition (that contains a v002 movie loader) runs fine in the qc viewer but when compiled with quartz builder it runs at an appalling frame rate. Tested on several computers, from 10.6 to 10.8. All the app does is play single movies at certain times of day, and the files play back fine from QuickTime player. It's also more obvious on lower spec machines, but fine in qc. Any ideas? Is the quartz builder overhead really that extreme as to get choppy 1080 h264 playback on a retina?