2) You need to enable TRIM manually by yourself
Code:sudo trimforce enable
I have the same issue, TRIM was always enabled but somewhere in the process of updating Mojave it became disabled. I have 3 internal SSD's (Samsung) and all have TRIM disabled no matter what I try. I even bought Trim Enabler and although it indicates "everything looks good" it remains disabled.
But here's the thing... when I boot into recovery command-R and try sudo trimforce enable in Terminal... it says "command not found".
Perhaps I have an old recovery partition, but not sure how to fix that or troubleshoot it.
High Sierra is sure looking good right now. Mojave has become frustrating.