Act 3’s issues aren’t GPU bound, it’s entirely CPU bottlenecked. It’s likely someone with a slower GPU won’t see as big a drop in performance in act 3 as you, and it’s likely you don’t see any performance gain from using DLSS in act 3. My 2080 Super was sleeping through it even at 3440x1440 on ultra while my Ryzen 7 3700x was getting thrashed.