Single thread overworked

[crystal knoll]

Running on Kubuntu 25.10, with Steam Runtime(scout) on Default Public Version (Sep 26, 2025), am seeing a single core being overused to 100% instead of multithreading

[small birch]

What situation is this happening in?

What area are you playing in? Do you use any mods?

[crystal knoll]

i am using mods, this is happening generally everywhere within panning over 150% zoom, in rosewood so far

is there any good way to debug this?

seems like its not mod related, booted vanilla and still experiencing the same

[small birch]

Can you test if it happens on the Unstable version as well? Since we dont accept bugs from older versions right now

I also do not suggest forcing any runtimes on the game

Run it natively

[crystal knoll]

@small birchretested, it is now less unstable(pun intended), but i still see the same behavior. However now its capping on one thread, and sometimes the other one caps

also disabled the scout and ran natively as you suggested, same result

(kudos to the team btw, even though that thread is still maxing out the performance improvement over the first video is clear, top left you can see lows of 50 fps, in the unstable i barely see my fps dropping to 58 instead of 60, framerate seems way more stable now)

[small birch]

Hm, I will try testing it on my own Linux later, can you specify your specs so I can compare with mine?

I assume it caps regardless of what you are doing or what the FPS is?

Meaning it caps if you lock it at 20 fps or even at 100+

[crystal knoll]

Ryzen 7 5700G
Nvdia 3060
32gb ram
990 evo equivalent

If you'd like I can try increasing the fps to 120 or something higher so we can rule that, it's odd that I have so many cores and GPU barely used(I assume this is fine since I've seen a few reddit threads say pz is mainly CPU bound), let me know if you'd like me to test something specific

[crystal knoll]

Will give that a try in a few

[crystal knoll]

unstable, 165 fps 1-2 cores maxing

idle (making sure nothing else is running on that thread)

stable, 165 fps 1-2 cores maxing

@small birch it is absurd how much yall optimized the game, the avg fps for unstable is 165 (cap) while the avg fps for build 41 is 40 fps (still 165 lock)

seems like the issue persist in the new build, although doesnt seem to be doing much impact to the game performance even with those 2 cores doing the heavy lifting (specially core 9 in my setup)

i also tried it with OBS turned off to get a more precise reading of idle vs game running, there is a 5-9% difference in each thread while the game is running, the 20% thread reaches seems to be OBS running in the background. Also removing OBS yields same result

[small birch]

How about the 20 FPS cap? I am mostly curious whether it is pinning the CPUs for no reason or if it does have a reason

At 165 FPS it would likely have a reason, since the CPU needs to compute the frames

Not all actions can be multithreaded, so one CPU will always be pinned once limits are reached, this is basically true for every game eventually, depending on how much of it is multi threaded

[crystal knoll]

@small birch same result it seems, 24 fps is the lowest i could go

[small birch]

Hm, I was unable to really reproduce it, there are times where a specific core gets to a 100, but then it gets switched to another core

Which would be normal

There is a bit of an anomaly that the single core gets to a 100 even when doing nothing at the main menu though

Whether that is on a single specific core or switches between cores would be dicated by the scheduler you use, I am on CachyOS instead so my scheduler is a bit different, which could explain why the cores are switching for me

You could forward it as an official bug report, since I would consider it worth investigating why the specific core is getting hit even when doing nothing
https://theindiestone.com/forums/index.php?/topic/43261-bug-report-guide-updated-18122025/

[crystal knoll]

That C8 graph peak was during the menu? I'm on kubuntu so generally should be well maintained, am curious to know if arch mint or another major distro has this issue.

Only thing I can really say is zooming to 250% exacerbates the CPU usage even at 24fps cap, but generally seems consistent. I did try some other games yesterday at night that are more CPU bound but couldn't replicate this behavior of 1 single core doing the heavy lifting at that amount

I'll make an issue for the menu usage high, you think it's worth creating a separate item for investigation for this behavior? I'd argue it's not really a big deal unless someone has a weak CPU, doesn't really seem like the game is running slower on the unstable build since I can reliably get 160 fps

[small birch]

Doesn't seem like a big deal, just something that shouldn't happen, I would assume it is the same problem whether in game or on the main menu.