^ if you read GameGPU analysis, they state that NVIDIA settings are God Rays and TXAA. With these settings on, the performance drop is 2X on Maxwell (!). They provided the data in their analysis.
1080p Ultra = 980 @ 97 fps
1080p NV (God Rays + TXAA) = 51 FPS
1600p Ultra = 980 @ 61 fps
1600p NV = 980 @ 30 fps
You can manually enable God Rays on AMD cards. In this game GR are made via tessellation. Not surprising that there is a major performance hit on AMD when TXAA + God Rays on Maxwell drop pefromwnce in half. Still, this game runs miles better than Unity which goes to show that Dunia 2 engine is just way more efficient than Anvil Next and the FC team just knows how to code way better. This game does look nice but not next gen enough imo. Still pretty impressive that FC4 on PS5 looks as good as FC3 maxed out on PC. Not bad for an underpowered console. AMD issued a statement that they are working with Ubisoft to get CF drivers working.