I have a 17" MBP, and I use FCP often. Is the jump from 4GB to 8GB of memory worth the money?

I have a 17" MBP, mid 2009, and I use FCP all the time. I'm a 20 year old kid, without a ton of money. The computer is working fine, but is just beginning to get a bit slow on me. From any of you out there who have done it, is the jump from 4GB to 8GB of memory really worth the money? If so, I'll do it.