High End PC Low End FPS

My specs:
CPU: AMD 3900X
GPU: RTX 3090 Founder’s Edition (I’m a GPU engineer myself and I got it from one of my classmates who works for NVIDIA)
Memory: 64G
Internet connection: 1000Mbps (128Mbytes/s)
Game installed on my Samsung 970 EVO SSD

And I’m getting 10-15 FPS even on low settings @ 1080p, with render rate as low as 50%. Strangest thing is, I’m getting 60+FPS on ultra-high @ 4k with zero issues when I’m running the tutorials.

I’m having zero issues with other games like DCS World, and I can also train neural networks or running CUDA programs with this rig at a pretty high speed.

Updating my graphics driver, doing a clean installation of the driver, switching off internet streaming in-game… none of these work.

Could anyone give me some advice on optimizing my performance? Thanks!