Verify integrity of files thats it thats all you need to do if it doesn't make sure it isn't some other mod doing it any mod adding units will have the super lag bug unless it was updated for the new dlc.

I'm making this discussion to highlight this to make it harder to miss because people don't read updated descriptions and my comments on this keep getting buried in bug reports which is why i want bugs the bug discussion along with some other benefits like the ability to reply.

1 Open your Game Library on Steam.
2 Right-click on your game.
3 Select Properties from the menu.
4 In the Properties menu, select 'Local Files' from the left-hand panel.
5 On the Local Files page, select 'Verify integrity of game files'
6 Steam will then verify your files. ...
7 Once Steam is finished, a box saying all files successfully validated.