I sent a performance report, just gonna add this here.
When I'm near a lot of tall grass, my FPS goes down to ~40. Otherwise, 60 most of the time but there are random drops also and lag when saving. Probably not as bad as some people are having.
My PC i5 6500 @ 3.20GHz, 32GB RAM, GTX 1080. My friend says he gets 60 FPS the whole time with a slightly worse PC.