I think this slow down relates to no trim support in OSX.
Just do a Time Machine backup, secure erase the drive, reload the OS and allow the setup utility to pull your data fro your Time Machine backup. That will bring the disc back to its factory performance.
Please, no secure erase and Time Machine restore. That's the worst thing you can do with an SSD drive. SSD drives are not hard disk drives. What you suggest would get rid of defragmentation, which is not much of a problem anyway, and is no problem at all for SSD drives.
lmao this is crazy i just ran repair disk, and onyx. and now im 80 write and 90 read............-______-
The more you flap around and test it and benchmark it, the slower it gets. For best performance of an SSD drive, just leave it alone. Start "Activity Monitor", Select "Disk Activity", see what happens when you actually _use_ your computer, for example when you start an application. Have a look how many reads and writes operations per second you get, and how many megabyte per second.
My main advice would be to stop obsessing about it...
Best advice ever. And good SSD drives will improve the layout of the data on the disk if they have nothing better to do, so the more you benchmark them without interruption, the more the performance will go down.