Smooth RAM Preview Playback

After Effects is not an NLE. You should not be editing movies in AE. The only efficient workflow is to limit your comps to a single shot or a short sequence, usually no longer than a sentence or phrase, then do your editing in Premiere Pro. More than 90% of my comps are under seven seconds because more than 90% of the shots in the movies and other projects I work on are less than seven seconds long. The average cut in a feature film now is just under 5 seconds. Even my Motion graphics projects (explainer videos, lyric videos) and music videos that are primarily produced in AE are no longer than a single phrase or idea. The only reason to have more than 1 shot in a composition is to create a transition that cannot be created in an NLE.

That said, just like Pixar, or ILM, or Disney, you need to adopt the Pencil Test / Ink and Paint workflow they all use. Nobody at Pixar or Disney tries to run full resolution full effects previews of their animations to see if things work. They run Pencil tests to check timing, framing, and movement with few effects, no motion blur, and at a lower resolution and even frame rate. You do that in AE by turning off motion blur, most effects, and even skipping a frame or two with the comp magnification factor set to 50 or even 25%. When the timing is good you turn on all the effects and motion blur and you check a few hero or critical frames to make sure things are working, then you send the file to be rendered. That's the Ink and Paint portion. When the shots are rendered, you drop them into Premiere Pro and fine-tune the timing, editing, audio, sound effects, and even final color grading to finalize the project. This workflow requires a good file structure and file naming workflow, you end up with a lot more project files and comps, but in the end, it takes less time, you are more productive, and you end up with a better product because you are not tied to a project that takes 7 minutes a frame to render every time you make a change. I can honestly tell you that I spend way less than 5% of my workday trying to run full effects previews that are longer than a second or two, and I use Render Garden to render every comp that won't render faster than 3 or 4 frames a second so I don't even wait for renders. I just "Pencil Test", check "Fill and Paint" on some hero frames or 1 or 2-second previews on critical sections or when particles are involved, then send the comp to the Render Cue/Render Garden and start on the next comp. The number of times I have to return to the comp and fix something is so small it is insignificant.

I hope that helps. Expecting AE, or any other animation and compositing app to work like an NLE is not a good idea. Even the major studios with their incredible budgets and multiple floors of huge buildings filled with render farms don't try and edit in their animation and effects apps. 

Sorry, but that's not how it works. You cannot force AE to do anything with excessive hardware. If it's not configured properly, even a shiny new system can expose the same issues. There's nothing wrong with your specs, even if by today's standard's they may not be the most powerful. Whatever issues you have have other causes, so take the time to sit down and straighten out the usual suspects - graphics drivers, cache settings and so on. Anything beyond that will require specific info about your actual preview settings, items and effects used in the project, composition settings, preview settings and so on.

Mylenium