Having big difficulties with lighting - mostly using only one dynamic light (moveable directional ligth - the sun) but its giving 30-40ms hit with my 4km*4km map. Is there something I could do to tweak the issue? Does landscape material affect - using tesselation much (with low fading distance).
EDIT: Getting better - found out how fast LODs and mesh amount also affect on lighting. Had also heavy basepass. Getting better, but all tips still wellcome.
90% of that time goes to rendering shadows. What is your shadow radius? How many triangles? Have you tested any shadow configurations?
Adding more to what Jenny said. You can play around with these console commands.
Note : There are no hard rules to use values that are mentioned here. Experiment and play around which suits your condition. Check for other things like traingle count, lods, material complexity and texture size.
r.Shadow.RadiusThreshold (0.03 - 0.06) (default is 0.03)
r.Shadow.MinResolution (32 - 128) (default is 32)
r.Shadow.FadeResolution (64-256) (default is 64)
Hope this helps.
Best Regards
Thank you both, 
have managed improve the FPS nicely. Many meshes had lods changing too slow and also removed many over-hungry meshes. Shadows are around 4 times less heavy now but will keep working on it. Could be I have some unneeded 4k textures on too that can be dropped. Those commands will be handly. Using currently quite similar shadow settings with kite demo (or the epic suggestions).
