on Jan 24, 2017 at 2:43:03 am Last Edited By Dave LaRonde on Jan 24, 2017 at 4:38:05 am
It would help to know how well you know After Effects.
But from your description, you simply need to do a RAM Preview of your Work Area, perhaps setting the Comp Window zoom to 50% and the resolution to Half. Maybe preview every other frame using Shift-0. That should get you real time previews.
If my description using common After Effects terminology didn't make any sense to you, you should start learning the basics of After Effects: