AI Stops "thinking" late game with 12+ nobles

I started to increase my kingdom size for a kingdom that has been going for ~50 years so far in order to provoke the ruler of the unending war.  However a couple years into having 12 people they sort of stopping functioning.

There is large bouts of time where everyone just stands in place, you can see their current action as if they are trying to do something but nothing happens.  The game isnt frozen as I can still scroll around issues commands que up crafting.  But the nobles just do not do anything.  Seems to happen similarly for enemies and NPCs.  The whole game ceases to function on the AI level.