To enable the TRIM support on OS X 10.9.5 for a 3rd-party SSD drive, enter the following commands into your Terminal session:
sudo perl -pi -e 's|(^\x00{1,20})[^\x00]{9}(\x00{1,20}\x54)|$1\x00\x00\x00\x00\x00\x00\x00\x00\x00$2|sg' /System/Library/Extensions/IOAHCIFamily.kext/Contents/PlugIns/IOAHCIBlockStorage.kext/Contents/MacOS/IOAHCIBlockStorage
sudo touch /System/Library/Extensions/Restart to enable the changes.