I got a macbook pro about 5 months ago, and just in the last couple weeks it has started running really slow. It gives me a pinwheel for a second, and then the mouse starts moving really choppy and typing is extremely delayed. If I plug it in to charge it, it's back to normal. Even when I unplug it, it's normal for a while but starts to get choppy after a while. Because of this I'm thinking it has something to do with the battery... Any ideas?