My late-2011 15 inch MBP came with 4gb RAM. I used it for a couple of months, and the lack of RAM power when using Final Cut, Serato etc was a bit frustrating. I upgraded to 16gb and after a settling down period of a week, it absolutely screamed with RAM intensive tasks. However battery life is MUCH worse. Before with 4gb RAM, I would easily get 7-10 hours of life. Now, it's more like 2-3 hours maximum - that's just surfing the net with nothing else even open. Admittedly I got relatively cheap RAM, so is that the factor in my battery life decreasing or is it just the general power-sucking nature of 16gb? Cheers in advance!