Ever since the Golden Grin update, anyone who plays with Shadow Quality below Very High has terrible flickering shadows. The solution? Download shadow map mod which reduces the quality of shadows, then put the Shadows settings on Very High, which should now be equivalent to Low quality without the terrible flickering.

http://steamcommunity.com/sharedfiles/filedetails/?id=183841516

v1 is compatible with ZDann's graphics tweak.