I found out the distance field shadows are causing in this build heavy stutter if playing in full screen. With 720p window FPS might be 60, but when clicking to full screen 1080p it may get to 1 (stat fps). Sometimes can get to ~24 but I dont think the hit should be like that. With 4.9 didnt yet have issue (but had different CPU, motherboard and memory then). Comp i7 5820K, X99-A, 32Gt DDR2400, GTX780, Win10 64bit, SSD 950pro.
DFShadows: Dist 10000, Sun Angle 1, Trace Dist 10000 (also tried with 1000), Depth Scale 0.003