I thought I'd chime in too to say I've got a similar issue with FPS. In Tuliyollal I'm getting 48FPS at certain locations (like at the Bayside Bevy Marketplace Aether looking north east, but many others exist). My CPU is capping around 70% and GPU is at 45%. Definitely not a hardware issue.

Specs:

intel i7 9700k @ ~4.6GHz
Asus Strix RTX 4090 OC
M.2 SSD
32GB DDR4 RAM (1200 MHz)

It's mostly fine and I'm getting around 165 FPS but in specific areas the FPS just TANKS and hardware monitors report no bottleneck.

SE plz fix