I also get way worse performance than the last two games, and the only thing that made it playable was cutting the resolution to 720. Not sure if that means it's expecting more video memory, or more video bandwidth.
Also, FYI, the opening area runs the worst of any section I've seen in the game (maybe 1/2 through). It's a real pain in the ass with the tutorial boss to have lag on top of it, but once you actually get into the firelink shrine and move on, things are way nicer, like 15 or 20 FPS faster nicer.