Hello all, I am hoping that someone here has experienced this issue and can help. The Computer I am running a late 2011 model MacBook Pro OS X 10.8.3 2.2 GHz i7 8GM RAM 1TB Internal SATA drive with several hundred GB free space The Issue For some reason the internal hard drive is running EXTREMELY slow. It can take up to 20 minutes or so to boot from power off to login screen and another 20-30 minutes to be functional at the desktop. Nearly every action thereafter is painfully slow. Attempted Resolutions I first went through the normal checks, how many apps are running, start up apps, active processes, memory used, etc. I had plenty of hard drive space, no background apps or services (under my control), 5ish GB of free memory, one app open, etc etc and yet still slow. I verified and repaired permissions (it did find a couple of errors), checked drive health (healthy), removed any unused applications, etc still slow. I decided I should give reinstalling os x a shot, did the upgrade version, no difference. Decided I should do a full wipe and clean install. I made a bootable backup to an external drive with Carbon Copy Cloner (very easy and useful app). I booted from the external drive expecting to just run the mountain lion installer from it, but the external drive boots and runs like the computer is brand new. Despite being an exact duplicate of my entire internal drive. Current Status The external drive runs perfectly, the internal drive is slow as hell despite the software side being exact duplicates. Does that mean the internal drive is dying or something even though disk utility says it's healthy? Do I need to replace the internal drive? or something else? Thank you to all of you who even read all this ;-) hopefully someone can help. UPDATE I have replaced the drive and reinstalled the os from scratch. The new drive, while being 500GB lighter, is functioning just fine. I put the old drive in an external enclosure and tried to boot from it. It takes forever just as before. So obviously it's the physical drive itself thats causing the problem at this point. Can anyone recommend a utility for the mac that can help me diagnose what would cause the old drive to appear healthy but run slowly? It's only a little over a year old.