As above. I’ve played 4-5 missions since the patch dropped and I’ve noticed substantial amounts of fps loss in many areas once hordes arrive.
Areas with lots of buildings such as the end event of Engines of War or the entire town in Empire in Flames seem to be particularly problematic. In these areas I’m seeing drops as severe as 50%. But even outside of those particularly troublesome spots I was noticing consistent minor fps dips when just fighting normal hordes.
I have pretty much all of my settings tuned for max performance as a matter of course. The only things I’ve left off of minimum are Texture Quality on Medium, Ambient Light on High, and Physics Debris at their default values.