After the recent hotfix I have been getting odd lag. The first time I encountered it was with a Minotaur using recklessness and then instead of attacking they moved away causing my game to lock up. Fortunately it was a random encounter so I was able to go back to a slightly older save and avoided that happening again. But later on Sorak mages would take forever to so their actions. And the one time I summoned an air elemental it too lagged in actions and then stopped doing anything after killing one enemy.
In a new game now and my dwarf archer is lagging every time she attacks with a bow. And from a steam thread this seems to be something one of the devs already noticed.
Now my PC is basically a potato so how the game runs for me isn't great. But this is clearly a bug.