Universal app is slower than non-universal app on iPad 3 because of opt-in for retina resolution

We develop our mobile air apps at two resolutions, 960x640 for phones, and 1024x768 for ipads. For non-retina phones we scale down, and for retina ipads we scale up.

We observe that scaling the content is worse performance than using requestedDisplayResolution = standard on ipad3. (Stage scaling SHOW_ALL being somewhat better than parentClip scaling 2x)

Our rendermode is ‘direct’, since ‘gpu’ caused problems for our content.

Presumably it is being faster to render to the smaller background with hardware on requestedDisplayResolution. That would be okay, except there’s no different requestedDisplayResolution between ipads and iphones. Setting the configuration to standard means we drop our 960x640 resolution setting on the phones. It’s that, or lose the universal app and have to ship separate builds, which is something we’d very much like to do…

Is there a way to make a universal app that is retina at 960x640, but not 2048x1536???