What's amazing is that there are parts in the Necromancer arc that go to 60 fps. The game, on average, locks at about 24 fps, the same framerate most movies are shot in. That's nearly a triple increase! o:
I think the framerate drop is due to the detail in the game. Save for the compressed Bink Video clips, the game is sharp and stunning visually. One of the best looking games this generation.