Corsair GS 180 slowdown in Macbook Pro over a year's time
How long did you have TrimEnabler running?  It will only help over time, when through deleting files the SSD knows that the file clusters are no longer needed.  

You can try to enable it, create a very large file (that takes up a significant chunk of your free space) and then delete it.

cd /tmp
mkfile 10240m 10Gigfile
rm 10Gigfile