Photoshop :: Video / Timeline Playback Quality Not Good In CS6 Extended?

I am using PS in a traditional animation capacity--drawing each frame of animation by hand on a seperate layer. I loved doing this in 5.5 and it worked wonderfully on my machine. There are a couple of problems for me with CS6 that perhaps
 
My main problem is that when i play back my animation (I prefer to use the clips/layers version as opposed to the "frame" version which is more limited in my opinion), the image quality is horrible. When I say "play back" I mean hitting the spacebar and playing it, not rendering it. This feature worked like a charm in CS5.5, but the quality is very low in CS6. The same thing happens when scrubbing with the play head--the image quality gets all blocky and pixelly looking. The funny thing is, when I stop playback or stop scrubbing through frames, the images go back to thier normal state.
 
When I first saw this happen, it reminded me of a low quality RAM preview in After Effects (for those of you who are familiar with After Effects)--which I thought would make sense, since AE offers a way to increase or descrease the quality of immediate playbacks (RAM Previews) depending on what you are testing in the playback and how much available RAM you have. But there is no way to adjust the playback quality in PS CS6--at least not one that I can find. I absoluately need playback to be 100% quality as it was in 5.5, otherwise this feature is completely useless to me.
 
Also--did they remove the "onion skinning" button from the Timeline window? That was so useful... That is such a useful button for anyone attempting traditional animation in this program--which it was wonderful for in CS5.5.

BTW--my current machine specs if that matters:
 
Mac Mini, 2009 model
2.26 Ghz Intel Core 2 Duo 64 bit
NVIDIA GeForce 9400 256MB
OSX Lion
4 GB RAM
100+ GB free HD space