I have a problem when I preview any type of composition on after effect (regardless size or time lenght), and since I'm kinda new in this program, I'm not sure if it's because of the RAM on my computer, or rather some AE preset that I don't know. I've already lower the resolution to 1/8, and to be honest I don't know what else I can do haha :').
Specs Intel(R) HD Graphics 520 4,05 GB RAM
Here's a video, hope it helps to understand the issue.
Pro-Tip: in that Preview panel, you can assign different hotkeys to trigger different kinds of previews! Assign one to be a low-rez, frame-skipper for quick & dirty assessment, another to the full-rez all-frames final look, and a few more to various stages of in-between, if you like!