Hi, I have a base 2012 MacBook Pro 13" with 2.5 GHz running Mountain Lion 10.8.3. Recently my computer has been running pretty slow, so I did a clean up of my hard drive. I have a 500 GB hard drive and I only had about 150GB free, so i decided to move a lot of my stuff onto my external hard drive. Now I use about 180GB and still have 315GB free. I have 4 GB of RAM. I have been noticing that it is starting to get slow. Applications start very slowly, applications do not respond. Even typing sometimes, I finish typing and then my computer lags a bit and then spits out all the words that I've typed. Anyone know what I can do to improve speeds? I don't really run heavy intensive RAM apps, at most, i only run safari, powerpoint, garageband, and/or iPhoto, and rarely together, and my activity monitor shows that i am leave AT LEAST 45 percent of the CPU idle. Usually it stays around 85-90. I am still confused as to why my computer acts like this.