Ok, I just finished Act 1, and the game runs perfectly fine on my system, with the exception of one very weird bug? I'm on a 980 ti, running the game at 1440p, and I've set upscaling to on, everything at medium settings. For the people who insist on playing on ultra, do not do that. Game is just unplayable at those settings, but on medium, it runs perfectly mine, at least on my system anyway. I don't know how to get the game to display the frame rate, but for the entirety of Act 1, from what I can tell, I was easily well north of 60 fps most of the time. I have a pretty good eye for frame rates, so I'm very confident this is accurate.
I'm on 364.72 drivers, using a gsync monitor, and the game is buttery smooth for the most part. The only odd problem I found was that through the entirety of Act 1, when I transitioned from certain scenes to another, the frame rate would tank and the game became super choppy. To fix this, all I had to do was pause the game and un-pause (sometimes, it would take multiple tries), and the frame rate would shoot back up to 60 fps and above again. I don't know if this is a gsync bug or what, but it's very bizarre.
In any case, I'll keep playing and see if my frame rates hold up, but so far, the game is buttery smooth on my system now and I'm enjoying the game so much more now because of that.
Sounds like you need to turn the textures down to High.