I updated to 10.8.3 the machine was unusable from the start. Istat menus showed that system apps were consuming memory in increasing amounts even with no apps running nor any user input. The machine was very slow and virtually unresponsive to mouse/keyboard input.
I "cured" the problems by reverting to 10.8.2 which is where I intend to stay for as long as possible.
Mac Pro, OS X Mountain Lion (10.8.3), 24GB RAM : SSD for booting and apps
I have the same issue with my mac, I updated to 10.8.3 and now it lags behind. When playing music, it keeps stopping and starting and apps take a long time to respond.
Wish I hadnt updated now
Try the standard stuff. Assumptions your hard drive is not greater than 80% full and you have more than 4GB of memory.
Run Disk Utility on your boot drive and verify/repair permissions. Then verify the drive while you are there.
In ~/Library/Caches, select the contents and move to Trash.
Start in Safe Boot Mode and let the system itself clear out caches, rebuild system databases (including fonts), and low level check your boot drive. Safe Boot is pressing and holding the shift key after the boot chime and until you see a horizontal progress bar. Once you have logged in, empty the Trash, and reboot normally.
Any performance change?
10.8.3 runs just as briskly and reliably on my 2011 Mac mini as did Lion and Mountain Lion 10.8.2.
To get to your user library to delete the Caches, hold down the option key while using the Finder "Go To Folder" command. Enter ~/Library/Caches
.
If you prefer to make your user library permanently visible, use the Terminal command found below.
http://osxdaily.com/2011/07/04/show-library-directory-in-mac-os-x-lion/
You might want to bookmark the command. I had to use it again after I installed 10.8.2. I have also been informed that if you drag the user library to Finder it will remain visible.
10.8.3 uncontrolled memory hog and slowdown
