Hey, even I had the same problem.. my shutdown speed became verry slow..
well i found a solution...
goto finder >> goto folder (⇧⌘G) >> type in "/Users/username/Library" without quotes and replace username with your user name..
>>goto the Caches folder>> move everything to trash.. >> secure empty trash...
VOILA! Your air will now have faster shutdown times.. worked for me..
Okay here's something I did that brought back the shutdown to 4sec
sudo defaults write /System/Library/LaunchDaemons/com.apple.securityd ExitTimeOut -int 2
sudo defaults write /System/Library/LaunchDaemons/com.apple.coreservices.appleevents ExitTimeOut -int 2
sudo defaults write /System/Library/LaunchDaemons/com.apple.mDNSResponder ExitTimeOut -int 2
sudo defaults write /System/Library/LaunchDaemons/com.apple.diskarbitrationd ExitTimeOut -int 2
sudo defaults write /System/Library/LaunchAgents/com.apple.coreservices.appleid.authentication ExitTimeOut -int 2
Quit Terminal and then reopen it. Enter the following:
I FINALLY FOUND THE SOLUTION FOR ME! (worked ever since that).
What I did.
1. Delete ALL the items in launch agent and launch daemons (in library,not system folder unless you want to reinstall the whole osx like i did).
2. Remove all the login items in Users and groups (found in system preferences). (i zipped the itunes helper app-control-select the itunes app in your application folder,in the osx folder you'll find the app and zip it or delete it)<zipping is for recovery option for future need>
Now the above were to make your start up faster so that it will not slow down your shut down time after you booted up your system.
The thing that really solved my problem is this.
3. Launch disk utility and perform a permision repair, and for me, the permision of java plugin always differ,so have to repair it almost every time(after restarted mac). so i decided to delete the plugin.
works like a charm for me
besides,do we really need java? (for me, fast shut down time with less than one second is more important)
HOPE IT HELPS~