Hello, I understand this has been asked before, but I've tried most suggestions if not all without any difference. Firstly, I've used windows all my life and moved to Mac afew years ago. So my technical knowledge of OS is minimal to say the least. So please be gentle. For the last couple of months I've been noticing my machine getting slower and slower. The only resource hungry app I have installed in CS5 with NIK, but this was installed well before the issues ever surfaced. My machine specs are: iMac 27inch Mid 2011 OS X 10.8 Mountain Lion 3.1GHz i5 1TB HDD 16GB RAM Steps I've tried: Reseating RAM Uninstalled unused apps Ran Onyx Repaired Permissions Unchecked "Login Items" Unchecked the “Animate opening applications” box I've checked Activity monitor, there doesn't seems to be high CPU or RAM usage. Please help..