Hello,

I changed the hair node parameter "opaque in shadows" to "yes".  The overall look is changed a lot. It's a lot faster (this image took only 10 minutes to render). The skin in the hair's shadow no longer shows the blueish tint. The back hair is no longer glowing (illuminated by the rim light), but shows much more the desired effect.

My only issue is now the bald spot on the forehead. I just don't remember any more how I got rid of that in the previous picture. I upped the hair density to insane numbers (2 million (a unit "meter"), that's 78000 hairs just for that hair prop), tried to mess with the root softness, no avail. Too bad I have no access to the setting which was active for the crashed render.

 

Best regards,

   Michael