you want to enable trim, supported with ext4 only, and disable atime, ie
- add noatime and discard in /etc/fstab (on my ubuntu machine it looks like this: default,noatime,discard)
- you can disable journaling with ext4
ext4 support 3 modes: writeback, ordered, journal mode
Do a search on the internet on how to enable writeback in fstab
I am not a big fan of disabling journals. I have had consistencies issues with ext2 on an unstable system.
For what it's worth, "mount" on Slitaz 4 shows / (formatted ext4) is mounted as ext2.
If i remember, in rcS.conf or whichever script gets executed first: / gets mounted readonly then remounted explicitly as ext2.
That would explain why slitaz was 25% faster on ios (compared to ubuntu on the same machine).
It means you have to check whether / is ultimately behaving as a ext2 or ext4 FS, since ext2 does not support trim. This is one of several reasons i stay away from slitaz at this time (no time to check for sure).
Trim to save on your disk, and is the only way to prevent your disk to become slower and slower because of the way ssd do writes (another way is to regularily backup reformat restore the disk).
In other words, I would investigate what i mentionned above, if I where you,
Hope this helps.