Hello everyone!
I’m new to Linux forums. I’ve been using Fedora since release 36.
Could somebody help me troubleshoot my issue?
Up to date Fedora 42, fresh install.
Whenever I launch Minecraft via Prism Launcher (flatpak) my CPU usage hits 100%. Same applies to Luanti. Stutters are noticeable even in the main menu. When a world is loaded the game runs at 0-4 FPS and F3 shows that GPU is always around 90%. System monitor reports Java using the entire CPU.
Besides that, my OS works just fine. The issue first appeared at the end of May 2025. I suspect some system component might have been upgraded to a version that handles my hardware poorly? Am I the only one affected by this?
I did as much troubleshooting as I could. Any further ideas would be helpful.
What I have tried:
updating the OS (Fedora Workstation) several times at a span of 4+ weeks
using a different Java version inside (Prism Launcher setting)
reinstalling affected programs - dnf and flatpak - no difference[1]
reinstalling mesa-dri-drivers
launching a different game (SuperTuxKart) - surprisingly it didn’t seem to be as much affected as mc/Luanti - it was playable - perhaps it depends on a different part of the system?
playing YouTube videos - no issues there
using an external monitor - on a bigger screen windows seemed to occasionally struggle, might be related
replacing Fedora Workstation with Silverblue. Haven’t tried to run mc/Luanti before rpm-ostree upgrade - I was certain the issue would be gone.
The issue cannot be a caused by faulty hardware because it’s not reproducible when launching Luanti or Minecraft[2]in live environment (Fedora-KDE-Desktop-Live-42-1.1.x86_64.iso). I didn’t test installed and up to date KDE yet. GNOME is definitely affected, both Workstation and Silverblue. I was certain the issue would be solved by installing a fresh OS version. Sadly, even this was to no avail. I have no idea what to do now. I could try to change desktop environment to KDE but honestly I don’t know how[3] and even if it would help, that doesn’t seem like a fix. I am also on a metered bandwidth at the moment.
Can somebody help me find the cause of heavy lags in visually “demanding” programs that used to run well a month ago? I can provide some logs if necessary.
edit: turned out something is not right. See here↩︎
edit: Luanti, installed as a flatpak, works on not updated Fedora 42 system (.iso 42-1.1 file). As the issue with Minecraft and Luanti is the same, I believe Minecraft would work in this environment as well. ↩︎
edit: turns out it’s super easy on immutable versions of the OS. Literally just rpm-ostree rebase fedora:fedora/42/x86_64/kinoite and reboot. ↩︎
Since 2D rendering (e.g. YouTube videos) is fine and a Live distro is fine, based on the other diagnostics you’ve already done, it sounds like 3D isn’t using hardware acceleration.
Tap the [F11] key to switch to fullscreen mode in Firefox. In the demo, on the left side there’s a floating control panel for adjusting the demo settings. How many fish can your system handle while keeping the FPS at 30 frames per second or higher?
10 000 makes it around 30-35 FPS
15 000 is 20-25
20 000 is stable 20
30 000 is stable 14
Fullscreen mode doesn’t make a difference, if that matters. Compared to a window taking roughly 75% of screen.
Edit: It probably doesn’t. Checked with Luanti, same window size as Firefox. It behaves in the same way but F11 does make it drop from 7 to 4 FPS. Probably because it’s more demanding than the aquarium.
Fullscreen mode was just to push the demo to render as many onscreen pixels as possible for a good baseline reference.
Try repeating the test in maximum windowed mode, but also open a terminal window on the same workspace with top running to monitor the CPU load. If hardware acceleration is being used, CPU load should be fairly low.
Interesting. I just copied what was shown to me in the settings. I can tell for sure that there is no discrete graphics card installed on this system, though.
Regarding the commands, is there a way to run them on Silverblue? It doesn’t seem to have those installed. Sorry, first time on Silverblue. Cannot go back to the Workstation at the moment.
Some laptops have dual integrated GPUs often with one being less energy efficient. With the right setup, you can choose which GPU to use when launching a program.
Using discrete graphics card (right click on Prism Launcher, second option):
[no minecraft screenshot as I am only allowed to post 3 in a single post, as a new user]
Yeah, I would’ve expected to see another VGA device in the dmesg output, but even without a NVIDIA GPU, your system at least meets the minimum requirements for Minecraft.
Which Java version is Minecraft using? (java -version)
the above screenshot claims the game use 3224x1926 and it looks like it’s running on llvmpipe software emulation. So it looks like it’s not using any opengl or vulkan HW acceleration. THis explains the awful performance.
It sayś mesa is version 25.1.3. F42 is still 25.0.7. So I guess this is a flatpak version?
For sure. It used to run smoothly 5 weeks ago. At least 30 FPS at all times, never ever below 20. One day it just started lagging. Even the loading screen before main menu is a slide show since then. I was sure I broken something but as we see right now, the issue persists on a freshly installed Silverblue.
I’m pretty sure it’s 21.0.7. The one automatically installed by Prism Launcher. I tried an older version back on the Workstation. Didn’t help.
Good catch! That’s weird. I wish I had a screenshot of the F3 interface back when the game run smoothly…
Yes, it is a flatpak version. I guess I could install it via dnf (now rpm-ostree) but I am fairly certain I already tried doing that back then with Luanti, which I found much more convenient for quick performance troubleshooting.
