From what I recall from one of their Directs, Digital Foundry corroborated another outlet’s finding that ultra settings (and I think specifically ultra shadows) are unoptimized. Tons of weird frame time jittering, and like a 15% drop in FPS compared to AMD. So, if you have shadows turned to High or lower, that’ll explain it. Otherwise, what they’re saying is an AMD equivalent would be getting 70-80 fps in your case.