Game performance degrade every league

Hi,
I have notice constant degrade in game performance every league.
I'm measuring my FPS every league in same spot at same settings, no mtx and it's around 7-10fps less compared to previous league. Graphics drivers are up-to-date. On maps it's barely playable where i have around 20-50 during combat. I remember on Sentinel league i had around 168fps in hideout(on Necropolis league only 120fps) and 60+fps during combat on maps.

Tested Vulkan/DX11/DX12 all have the same issue.

Computer specs:

CPU: i7 6700k
GPU: GTX 1070
RAM: DDR4 32GB 3000MHz

Game Settings:




Testing spot: