Quote Originally Posted by One_Hertz View Post
What he is saying is that the command is sent right after a delete to mark the relevant cells as empty... We do not know when the cells are actually erased on the NAND level.
When an application hangs you can be fairly sure the TRIM command is being executed in some form at the SSD level. Even if its not being executed at the NAND level the drive is inaccessable just after a large delete.

A wild guess. It is not the TRIM operation that takes the time, it is SF processing time. TRIMing a drive full of Ofil data takes the same or more time than TRIMing a drive full of non compressible data.