tokala
Emperor
As I mentioned earlier my belief was that unit spawning (particularly barb/demon spawning) may be the reason for the crashing (crashes certainly seemed a lot more common after I switched to Hyborem and the AC started ramping up), so reducing their frequency would reduce the frequency of the crashing. Obviously this is not a final solution and it would be better to solve the reason for the crashes than simply reduce their frequency because of a wild guess I have.
Disabling lairs and the "no unique features" let me play a total of some 1000 turns over the weekend. Only one crash, after the AI managed to pop a named monster out of a hill giant fastsometing.
Barbarian+animal activity was set to standard.
Usually I would had a few dozen crashes in this timespan.
So it indeed seems that someting related to the spawning of "special" units is inducing the "random" CTDs.