So I just started using AE and I've noticed that previewing my video takes quite a long time to render. Also, while using AE, other programs I run, such as Chrome or VLC media player, run slower than usual. Here are my specs:
AMD 7870 XT
Will increasing RAM boost performance, or will my CPU bottleneck. Also, is there a way to utilize my powerful GPU?
It looks like your processor has 4 cores. If you increase your RAM, you would be able to improve your multiprocessor activity - typically I recommend 3 GBs of memory per core. Plus, you have to account for the needs of the OS and other applications. Multiprocessing can speed up many activities and improve render times.
Like Greg said, 3 GB minimum per core and make sure that you have read the optimizing your system for CC documents. I've seen so many folks end up with Zero in the number of CPU's actually used portion of their preferences. It's easy to do if you don't pay attention.