Running ML, but was the same on Lion. Background: A straight disk-swap was done from a mid-2009 MBP 17 to a late-2011 MBP 17. This caused some issues with the user account which were resolved by the following steps" - Repaired disk - Zapped Preferences folder from Library Since then, all was fine, but the account is sluggish compared to another account on the same machine. Eg. Select System Prefs from the Apple menu, and it takes 2-3 seconds to appear, while it's instant in the other account. Any thoughts on what else to try? I'm very reluctant to start again with a clean install as I suspect Migration Assistant would likely bring back whatever is causing it, and starting from scratch, reinstalling all software, reconfiguring the machine, etc, would likely take more than a day's work.