Thank you tiktoc for advices, in fact I already seen that advices by Prattler and was about to try them. I'll also try with p2pool ver. 11.3
I think it will be better to swap back to 8.1 because bitcoin-qt crashed for not enough memory (I have 8 GB...) and python crashed. It's very unstable...
Now I'll try with prattler parameters, 8.1, p2pool 11.3 and will post results here