Using DX11 seems to solve the problem almost completely.
I’m considering to move to Dx12, but my problem with it is that it’s slower than dx9, especially when rendering skeletalmeshes. In my 100 bots test, dx9 gives 130 fps, and dx11 40 fps… but in the game the difference seems lower, with the skeletalmeshes more disperse, I think.
Also there are some good things like SSS. There are a problem with the specular in materials, but it can solved easily and with no extra performance loss: Specularity loss using movable light - Epic Games Forums