Speed up your OS... turn Autosave & Versions off globally
If you're experiencing slow opening apps or windows since upgrading to Mountain Lion... as I have... and you don't want your OS to automatically save your TextEdit files, etc. then simply disable Autosave and Versions via Terminal.
Open Terminal and enter this command which will turn off Autosave & Versions globally:
defaults write -g ApplePersistence -bool no
Now reboot.
Voila!
I experienced a very noticeable speed increase when opening apps and even opening some previously slow opening Dock folders after doing the above.
If for some reason in the future you want to turn Autosave and Versions back on just change 'no' to 'yes'
Feel the speed!
iMac, OS X Mountain Lion, 27" iMac 32" secondary monitor