Ya, the default affinity was choosing virtual threads instead physical ones. Damn! 6MH/s!
All Ryzen users should take note. Intel chooses one thread per core before using HT.
I confirm major performance increase with Ryzen in scrypt adding --cpu-affinity 0x5555
From 22 H/s to 29 H/s with 8 threads and from 28 to 35 H/s with 15 threads!