You have disabled buffering with buffer mode 3. A minimum of necessary data still goes into RAM. With memory size 0 you will use microSD instead of RAM. To avoid an early death of your microSD, use memory size 0 just for testing, not for permanent usage.
What's the result of your overclocking test?
Which LE version do you use for testing?
Does pastekodi show any unusual output when you get audio errors? If yes, post the link.H
Here is a link to a Pastebin of the log of the current stable version of LibreElec while watching an episode of Star Trek: Enterprise. It usually has the audio stutter toward the end of the episode (note: stutter happens on Patton, the movie, as well as on other things randomly) and it happened around 01:37:43 PM or so and stuttered ever so often through 01:41 PM. I have included that log portion here for you to look at. Could you please see what you can see? I don't know what I am looking for. So I don't know if it seems to have an error or not. This is before I force turbo. Working on that now.