Setting "MaxPhysicsThreads" greater than 1 causes unusual high CPU usage, especially when server is empty

[viaguy]

Game Version

v1.20.1

Platform

Linux

Modded

Vanilla

SP/MP

Multiplayer

Description

MaxPhysicsThreads set to 1. One player online, standing still
The CPU usage is the same when the server is empty. Everything seems normal to me here:

MaxPhysicsThreads set to 8. One player online, standing still
Here we see 7 threads using higher amounts of CPU during the exact same situation as before:

MaxPhysicsThreads set to 8. Empty server:

I did test other values for MaxPhysicsThreads like 2, 4 and 6. The result is the same, just less pronounced.

How to reproduce

Here is what I did to confirm this issue is present in a vanilla install and wasn't caused by any mods I am running on my server:

Download the official linux server for v1.20.1 from vintagestory.at
Extract to an empty directory
Run the server once to generate the stock configuration json files
Edit servermagicnumbers.json changing only "MaxPhysicsThreads" to a number greater than 1.
Restart the server and observe detailed system CPU usage using something like htop

Screenshots

No response

Logs

Logs if you want them. Though I did take a look through them and I didn't see any helpful information.
server-debug.log

server-main.log