It seems that there is a very drastic incompatibility now between the Mystical Travel Shelf Mod and the newest version of the game.
Trouble shooting I did was a total uninstall of the game, via steam, plus deleting everything else under the Conan Exiles directory (after moving my save games).
It then seemed to run ok again, mostly. I then added in the MTS mod again and the game would now freeze after about 6 minutes of play. So it’s probably that mod. Probably.