I think this issue is connected to this: UE 4.12 is the worst build for mobile VR - massive performance issues out of nowhere - XR Development - Unreal Engine Forums in a sense that without my setup for normal map, I either get no normal map or corrupted normal map or nice normal map with horrible performance when looking straight down on the terrain while standing on it (if I get away from the terrain and look down from above, I get no performance drop)