I have a 3.0 GHz P4 that is hyperthreaded with 1 GB RAM. I loaded and animated a 6-layer .psd file that was 1748x2480 as a sequence. When I started to animate the layers, performance was very slow. BUT, and this is a very big *BUT*, that was only when I had the Playback Quality settings to High or Automatic. As soon as I set PQ to Draft, response in the timeline was almost instantaneous. Here's a rundown on what the PQ settings mean: 1. High - Playback and still frame are shown at full resolution (in this case, 1748x2480). 2. Automatic - Playback is shown at Draft quality resolution and still frames are shown at full resolution. (This will explain why RT playback of these huge images performs better than just jumping from frame-to-frame.) 3. Draft - Playback and still frames are shown at 1/4 resolution. Performance is great at this setting. My recommendation - animate these huge images in Draft to start with, fine tune as necessary from time-to-time in Auto or High, and don't expect the final render to be done during the new episode of Spongebob.