What mods are you using?
With EUI and huge map, you must be running close to the RAM limit.
Only EUI, the standard package for the comunity patch and 3rd/4th component mod. While it obviously pushes things a bit to the limit, the test I did previously was without any mods (aside from comunity patch). Setup was duel map on quick speed (wanted to test out some stuff).Ran into the same EUI shenanigans, and the trade routes too.