升级10.8.2之后镁光M4ssd Trim Support被关了，关机慢的可以试试

Enable TRIM on non-Apple SSDs in OS X 10.8.2 Mountain Lion.
WARNING: This is ONLY tested on 10.8.2, and NOT earlier or later versions. YMMV.
注意！这个方法只在10.8.2中试过，其他版本照搬此法的话，效果可能会大相径庭！！慎重！！！
Technical note: The driver changed in 10.8.2 and similar perl commands that worked in earlier OS X versions did not work for me once I updated to 10.8.2.
Run the following commands in Terminal…
1. Backup the original driver
拷贝原来的硬盘
sudo cp /System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage /System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage-backup
2. Modify the driver
更改硬盘
sudo perl -pi -e 's|(\x52\x6F\x74\x61\x74\x69\x6F\x6E\x61\x6C\x00{1,20})[^\x00]{9}(\x00{1,20}\x4D)|$1\x00\x00\x00\x00\x00\x00\x00\x00\x00$2|sg' /System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage
3. 2 commands to clear the system caches to enable OS X to pick up the modified driver
清理系统缓存
sudo kextcache -system-prelinked-kernel
sudo kextcache -system-caches
4. Restart the Mac
重启
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亲测可以用，air终于又秒关了，开心！