Both guides you link to have you enable the
discard mount option for your filesystem. In my experience, this kills performance. On every sync after a file has been deleted, a TRIM request gets sent, causing the disk to freeze up for 2 to 3 seconds. (This will be hardware-dependent.)
To see whether this is the problem, try testing
fsync performance as suggested in this thread:
Running Theodore Ts'os "fsync-tester" while doing Linus' torture test
while : ; do time sh -c "dd if=/dev/zero of=bigfile bs=8M count=256 ; sync; rm bigfile"; done
shows it clearly
Sync should be fast on an SSD. In my case and that poster's case, each sync causes a lockup of several seconds. See also https://patrick-nagel.net/blog/archives/337 for a similar example.
If you see similar behavior, you should disable automatic TRIM by removing the
discard option from your fstab. (But keep the
relatime option that you probably added.)
Instead, periodically run
fstrim on your filesystem, e.g. using
cron. Several ways to do this are given in this article. This way you should still get the benefits of TRIM without the performance problems.