Hey there, demodom.
Basically those tweaks you've tried are pretty helpful (some even obligatory, one might say - like enabling TRIM). If you have any suspicions that the SSD might be having issues, I'd recommend that you backup any personal data you might have on it, just to be on the safe side. After that, download an SSD diagnostics tool and test the drive for errors, to see if anything unusual pops-up. You could also try the SSD with a different computer, or at least with a different SATA port and cables on yours. I'd also suggest that you check if there's a firmware update available and if there is one - install it to see if that fixes the problem.
Hope that helps. Please let me know how everything goes.