[Performance] Progressive FPS Drop from 120+ down to 30FPS during Combat (i7-12700KF / RTX 5070)

The game runs perfectly fine initially at 100+ FPS / 144 FPS (even idling in town for 30 mins is fine).

However, as soon as live combat begins, the FPS suffers a progressive,irreversible degradation, dropping down step-by-step: 144 -> 96 -> 60 -> 40 -> 30 FPS.

Once it hits 30 FPS, even returning to an empty town/hideout does NOT recover the frame rate; it stays hard-locked at 30 FPS.

CPU : Intel Core i7-12700KF
GPU : NVIDIA GeForce RTX 5070 (12GB VRAM)
RAM : 32 GB
OS : Windows 10
Storage : WD_BLACK SN850X 4TB NVMe SSD

Seeing this as well on a 4070 / ryzen combo. Both on 59x and 610 drivers from Nvidia.