[1.4.3525 64-bit] Vanilla - All DLC : Game Stuttering / Lagging every 2 seconds

[CoreV]

Issue has started only mid-game on new DLC / 1.4 update.  Issue has happened immediately with no problem up until the current save, previous auto-save is fine.  Game stutters / Freezes for a frame every 2 seconds on fastest speed, it goes slower but just as regularly at slower speeds synced to the ingame clock.  Issue is specific to this save / something that changed in this save.  Only notable change is recruited a child from being a prisoner, making three children pawns in total. 

Gamesave file should exhibit the bug continually, restarting the game had no effect.  Issue had occurred far less regularly a little earlier in game but after restarting PC issue went away.  Issue remains on this game save, others continue to work fine. Mods were installed but issue remains with mods removed, same mods were used without issue on an earlier version.  Gamesave is fresh from new update / DLC.

I'll try the earlier auto-save and report if the issue reoccurs, but wanted to report incase it's a bug and not just a one off issue.  Thanks for a great game!

Game save -  https://drive.google.com/file/d/1WFlaV6rJZ_l-P3BCaIFFsHmG0vVyj34c/view?usp=sharing   

EDIT:
So I banished the new child that I had recruited, that seemed to fix the issue.  I guess I'll see if the issue starts again if I get another third child.

EDIT2:
The issue came back a bit later, no new pawns. Not really sure what to try next.

Edit3:
Issue still occurring on latest update, steam forums now have a few other posts mentioning stuttering with one suggesting it is related to large pens and was fixed by reducing it, I do have a large pen so will test.