It dirrectly effects how long things take to render. May not seem like 10 or 15 sec a frame difference is that big of a deal, but once you get an animation ready to render that is thousands of frames, its kinda nice to have a fast processor. So... It kinda depends. Most of my compositing shots are pretty short, so if it were me I would get the ram, but it depends on how much stuff you may have for rendering. Hope this helps!
Brian