Patch 1.1.0 is now live and no longer in beta. This includes a fix for campaign map stuttering, as well as babies being more likely to be born from marriages and many battle AI fixes and behavioural improvements.
You can view the patch notes here: https://www.totalwar.com/blog/total-war-three-kingdoms-patch-1-1-0/
If you were on the beta, please opt out of the beta and restart Steam to ensure that the update takes effect.