I've had my Macbook for a few years now and have noticed a big performance drop. For example, it would take me about 30 seconds to boot up and now takes me about 2 minutes. I've noticed with PCs in the past that a reformat or reinstallation of the operating system usually speeds things back up, so I was thinking of doing the same thing with my Mac. I do have an external HDD so that I can just move all my media and documents over to that, then transfer it back when I reinstall OS X. Is it worth the time/effort though?