When I was using Lion on my rMBP, the shut down time was especially quick and the screen just switched off within 1 sec upon pressing the button. With ML now, shut down time is in the range of 5-10 secs and there is always a grey screen with a spinning wheel before shutting down. Did anyone else experience the same? ML feels sluggish to me even with a clean install.
It sounds like you may have an app that's hanging. Launch Activity Monitor and change "My Processes" at the top to "All Processes", then look to see what may be hanging.
Thanks, but how do i know what app is hanging based on the processes list? Update: It does feel slightly better now as the shut down time is reduced to 2-3 second, but I didn't anything at all