Periodic frame hitching when moving with engine multithreading

Hi all.

With this latest league, I'm facing constant periodic frame hitching/freezing every second or so when moving around. After playing around with my options, it seems to be tied to the engine multithreading.
I'm using Proton experimental.

Debug graph when multithreading is ON and I'm moving:


Multithreading ON and NOT moving


Multithreading OFF and I'm moving:


My system is:
Processor AMD Ryzen 9 3900X 12-Core Processor
Memory 65800MB (35151MB used)
Machine Type Desktop
Operating System Ubuntu 21.04
Resolution 5120x1440 pixels
OpenGL Renderer NVIDIA GeForce RTX 2060 SUPER/PCIe/SSE2