So if I understand this correctly, TRIM only works autmatically from the moment on that you install the firmware (assuming that you are running Win7 or else it can only be done manually). But the garbage already on the SSD is not deleted, that only happens when you actually delete a file or format the SSD?

So you have to use the manual TRIM command from the toolbox once to get the new state performance back. That, or a complete format.