Some effects take a long time to render. It is not unusual for a single frame to take minutes to render---for example, when working in 3D or if certain effects are used.
If you had a computer with more RAM, then I'd recommend that you use Render Multiple Frames Simultaneously multiprocessing in After Effects to render and export the parts that you need from After Effects.
See this page for resources about making Adobe Premiere Pro and After Effects work faster:
http://adobe.ly/eV2zE7
---------------------------------------------------------------------------------------------------------
Todd Kopriva, Adobe Systems Incorporated
After Effects quality engineering
After Effects team blog
---------------------------------------------------------------------------------------------------------