Gave DD2 another go after its third patch and I can now report: at least in the areas I visited, frame rate has *vastly* improved. It used to chug any time I was near grass, but now it hardly stutters at all. It's even stable in bakbattahl with all the npcs milling around now. Haven't been to vernworth and its surroundings yet, those used to be the worst for me. But this is promising. Even fighting giant bosses doesn't tank the frame rate anymore. Sadly the game still crashes any time I try to do anything related to vocation though. Still isnt running perfectly... but a lot better than before, at least. I'm in the last legs of the main story now.
