Ok, I tried XMR-Stak-CPU miner with i5-7200u and the result was .... 31h/s

Should one use some very specific settings or something? i7-7xxx are supposed to get around 700h/s so there is a chasm between those two results

What is wrong with You??!?!? I5 and only "U" what is 15W max, this is like Celeron or Pentium processor, You never have more Hashes with XMR.
I have 3632QM with 35W and make 110-120H/s.
And You say 700H/s have anybody with i7??? Must be very very good CPU:
http://prntscr.com/ijaf9a