Massive Lags - Unplayable performance (FPS Drops)

so a baseline my PC rig (don't tell me to upgrade it for poe)
I9900k
2080
SSD Samsung 970 pro

FPS drops to 40-20 are frequent in any endgame map content. I have fully leveled atlas. With all the things exploding and rapidly moving on the screen anything below 60FPS is not playable.

I don't understand why a 15 years old game should lag on a 3 year old PC, with 3 times lower FPS on lowest settings, than Cyberpunk and Witcher on Ultras.

I have tried all dx11, dx12, Vulkan, deleting cache folders, reinstalling newest drivers. Nothing works. DX12 is the most stable of the three, but overall performance has been abysmal. I also had massive lags in tota, despite it not having a massive amount of mobs. With FPS often being stuck in 30-60 range.

I never had issues during leveling and campaign and early mapping. My build is tornado shot projectiles fire, that alone tanks FPS from 200 to 120 in hideout. But mapping is absolutely horrible experience. WIth FPS being stuck in sub 20-30 zone and mobs not loading visually properly on map.

Performance optimization is the main reason, I went from giving like 8/9 out of 10 for this game to like 0-1 score. It is not tolerable or acceptable. There are lots of bad things in this game like an overgrinding mechanics or gacha/gambling, but nothing is even close to this.

I have watched a dozen of streamers and players with even better rigs than mine and saw them all lag miserably, and try to not pay attention to it, whervever a pack of mob spawns or dies.