I am experiencing that also, including random screen refreshes (switches between 24 frames and 60 frames).
I removed all network stuff (buffering etc) from advancedsettings.xml and cleared autostart.sh from all ethtool settings. That seems to work for me right now, although there are still micro freezes (fraction of a second) every now and then.
First of all, thanks vpeter (and the LE team ofc) for keeping my Cubox-i4 Pro working!
I have been testing all the different versions of LE on my Cubox-i4 Pro (Original 8.01, vpeter Xbian 4.4-8.0, vpeter Xbian 4.8-8.01, vpeter 3.14-8.01) and 3.14 version is the only one working like a charm. I do not have the blank screen problem like others seem to have, but all versions besides 3.14 have a delay in video rendering while watching movies or series. The problem is the same regardless what FPS i use (tested 24, 25, 30 50 and 60).
Using "Adjust display refresh rate to match video" and/or "Sync playback to display" doesn't make a difference. I use 3.14 with "Adjust display refresh rate to match video" on and i can watch everything without a hitch.
I have no idea really why 3.14 works for me, although i read another post, that LE uses an "inbuilt" advance settings file under /usr/share/kodi/system/advancedsettings.xml, which has
<delay>175</delay>
in it. The 3.14 version has that file but not the delay. I do not know if the other versions have that delay, because i found out after testing them.
All in all, don't stop making the 3.14 version vpeter, it works for me :).