I have a MacBook Pro ( mid-2012) and I was wondering why does my computer do this when I open it. It has been doing this for awhile but not always. I would hate it if it is an internal problem and I don't want to go to an Apple store. What happens is that when I open my laptop, it "boots" up and becomes laggy until about 15 seconds. How do I get rid of the booting? If this thread is already circulating through the forum, I do apologize. It is not easy to describe something that you don't know.