My 9 mos old MBPro often gets real slow and jerky. I go to the activity monitor when this happens and the CPU usage window looks like nearly solid green building blocks. I assume this means something is taking up a lot of CPU room. Can anyone explain what I'm seeing? If you can tell me how to post a screenshot I could show you what it looks like. Is there someplace I can learn how to use the activity monitor utility explained in simple terms? I just don't know what to look for or what I'm seeing. Be gentle....I'm an old gray grandma.