Alpha cutout masks was my fault :) It was about sun size.
I'm experiencing problems with displacement. Here it has to be a 3cm displacement and it's not creating a good effect.
I tried with 20cmx20cm subdivision and 10cmx10cm subdivision. It's the same. With almost no subdivisions it was a bit worse.
Vray is working perfectly with 20cm x 20cm, Advanced Render too (both with subdivision settings inside the material). Octane needs no subdivisions. Same map of course
Now I tried with 2cm x 2cm polygons subdivision and it's better. With 1cm x 1cm subdivision it's almost perfect. But it's crazy to subdivide a real world scene into 1cmx1cm polygons to get a good displacement. I guess we need material subdivisions too :)