Hello, so I've had my Mac OS X Tiger for a few years now, and it has always run beautifully despite that I'm not exactly a gentle owner. The past two months or so it has been running really slowly most of the time. Sometimes like now, it runs fine,but other times I'll type a paragraph and the letters won't show up on the screen for another thirty seconds. I ran a virus scan and it said the system was clean. I know they automatically defrag 20 mb or less but should I be defragging the rest? I have no idea what I'm doing. I use it for college, facebook, and occasionally movies. It has to last me another three years at least though, any ideas?