Went to BIOS and changed the scheme from daily use to gaming and multimedia and voilá, instant improvement. Allthough there is still some issues, but little tweaking should help that too. Motherboard is Asus ROG Strix Z370-E Gaming and it comes with BIOS GUI with easy of use, if someone has similar problem, its very easy to fix it there. Thank you for help and that LatencyMon tip! Cheers!