I use a 13-inch 2010 Macbook Air. My MBA runs perfectly and I never experience delays or crashes. I'm also a simple user - surfing, reading and writing. Ever since I updated to ML I have been experiencing significant lags when accessing different programs - from browsers to simple programs like evernote. Often, my MBA will lock up and the cursor will be that little multi-colored ball and it will sit there and spin for 10-30 seconds. The performance on my MBA has really gone downhill as well as it does not feel nearly as quick as it was prior to the upgrade. Anyone else experiencing these kinds of issues? Any suggestions on a fix? Maybe a clean install to get her running back at top speed? Edited to add: figures, after I post this, I came across the following post with discussion on this topic. http://forums.macrumors.com/showthread.php?t=1414960 Think I will figure out how to do a clean install!