poe has low gpu cpu usage

so in the last two leagues my poe was fine and i could run delirium beyond maps with 40 fps medium graphic.
but after leaving the expedition for a while and coming back in scourge my cpu and gpu usage have got realy low and my games is lagging in towns with the least graphics.
i have made my power management mode to prefer best performance and my power settings on best performance too. but that had no effect on the game. also checked that my game is running on the right gpu and my drivers are up to date and this problem is only hapening in poe.
and i dont think the cause is bottleneck cause my cpu is i7 9750h and gpu is 1660 ti and average heat is 78-80.
what should i do to fix it?