Upgrading RAM to run games better?

So my girlfriend has a Apple MacBook Pro "Core i7" 2.66 15" Mid-2010 and plays the Sims 3. She has all the expansions and plays for hours about 3-4 days a week. Lately, however, she has had pretty bad fps lag. She lowered her graphics basically down to the lowest settings and still has the problem. It seems to have gotten progressively worse as she plays. I was wondering if upgrading her from 4 to 8gb of RAM would show a significant increase in performance.

That may solve the problem but your processor is the best you can get. i7's should handle it with ease. But ram won't help your graphics card witch may be the source problem. It could be defective or had a lot of wear and tear. Ram wouldn't help the problem much.