Those are very useful points, thanks! But Id like to notice that if a common user tries to follow this rules, he will most probably harm his Macs system. That's because changing system files to speed up a Mac is a hard thing to do, as in most cases you will get nothing except more troubles. So if you are not a super geek I would recommend using a third-party utility, which will do all the things mentioned above safely, easy and with only one click. My choice is CleanMyMac by MacPaw. I think it is a good one, as I've heard of lot of positive reviews about this company, especially on their Facebook fan page . And also MacPaw creates an interesting and useful apps. Hope this info will be helpful for someone