Ubuntu 18.04 LightDM / Openbox. Automatically installed Compositor?

Does lightdm or xorg or openbox automatically install a compositor on 18.04?

I ask because awhile back I upgraded my server / htpc to 18.04 and had washed out video and out of sync audio. Mythtv was the worst playback of anything. Rolled back to 16.04 and everything was fine. Last night I was tinkering with something and added compton and the problem came back. Stop and remove compton, problem solved. So I'm thinking somehow a compositor is being enabled on 18.04 that I am not aware of, and it is messing with Kodi.

This issue is holding me back from upgrading to 18.04.

*EDIT* Software selection is very basic. Ubuntu server LTS with Xorg, Openbox, Lightdm, Kodi. Lightdm autostarts Openbox, which autostarts Kodi. Nothing fancy with gui stuff. Direct Kodi load while being supported on the Kodi forum is my goal.

You can globablly disable compositing by saving as /etc/X11/xorg.conf.d/70-extensions.conf the following:

Section "Extensions"
        Option          "Composite" "Disable"
EndSection

Some popular DEs will black screen or freeze local keyboard and mouse on attempt to start if you use this (e.g. Plasma).

Tried it. Am sitting at a fully upgraded machine, all worked out and migrated to netplan. LightDM wouldn't start with that file in place so that was a bust. I will keep researching this, or hoping for more ideas. THank you though.

*EDIT* Just now managed to get on the tv, wife was watching netflix. Same problem as compton. Mythtv playback is terrible and unwatchable. Other media seems fine but considering it is identical to what happened when I tried Compton, I'm thinking some kind of compositing somewhere is doing this.

Is there a way to determine if compositing is enabled or not? That way I can try to isolate whatever it is?

I've rolled back to 16.04 on my lvm snapshot. Until I can sort this out my upgrade is on hold unfortunately. Same issue persists. Looks like I'm going till 20.04.