Bug 506892 - Plasma becomes quite laggy after several hours of usage ever since upgrading to Plasma 6.4
Summary: Plasma becomes quite laggy after several hours of usage ever since upgrading ...
Status: REPORTED
Alias: None
Product: plasmashell
Classification: Plasma
Component: generic-performance (other bugs)
Version First Reported In: 6.4.2
Platform: openSUSE Linux
: NOR normal
Target Milestone: 1.0
Assignee: Plasma Bugs List
URL:
Keywords: regression
: 507670 507992 (view as bug list)
Depends on:
Blocks:
 
Reported: 2025-07-10 23:37 UTC by lesaysthismailisforbugzilla
Modified: 2025-10-10 23:39 UTC (History)
5 users (show)

See Also:
Latest Commit:
Version Fixed/Implemented In:
Sentry Crash Report:


Attachments
Output of journalctl -b 0 _SYSTEMD_USER_UNIT=dbus-broker.service (3.41 KB, text/plain)
2025-07-12 02:29 UTC, lesaysthismailisforbugzilla
Details
Screenshot of the graph created by Bustle as I was removing one txt file (1/7) (210.23 KB, image/png)
2025-07-19 21:41 UTC, lesaysthismailisforbugzilla
Details
Screenshot of the graph created by Bustle as I was removing one txt file (2/7) (180.83 KB, image/png)
2025-07-19 21:41 UTC, lesaysthismailisforbugzilla
Details
Screenshot of the graph created by Bustle as I was removing one txt file (3/7) (231.60 KB, image/png)
2025-07-19 21:42 UTC, lesaysthismailisforbugzilla
Details
Screenshot of the graph created by Bustle as I was removing one txt file (4/7) (228.78 KB, image/png)
2025-07-19 21:42 UTC, lesaysthismailisforbugzilla
Details
Screenshot of the graph created by Bustle as I was removing one txt file (5/7) (212.78 KB, image/png)
2025-07-19 21:42 UTC, lesaysthismailisforbugzilla
Details
Screenshot of the graph created by Bustle as I was removing one txt file (6/7) (229.96 KB, image/png)
2025-07-19 21:42 UTC, lesaysthismailisforbugzilla
Details
Screenshot of the graph created by Bustle as I was removing one txt file (7/7) (113.82 KB, image/png)
2025-07-19 21:42 UTC, lesaysthismailisforbugzilla
Details
Crash info from killall -ABRT plasmashell (220.94 KB, text/vnd.kde.kcrash-report)
2025-07-19 23:16 UTC, lesaysthismailisforbugzilla
Details

Note You need to log in before you can comment on or make changes to this bug.
Description lesaysthismailisforbugzilla 2025-07-10 23:37:50 UTC
SUMMARY
Ever since I've switched to Plasma 6.4, I'm experiencing the following issues after several hours of normal usage:

* Notifications stop working. I can hear the sounds for Discord for example but nothing pops up. Notification indicators "freeze" too.

* The panel and the applications menu become unresponsive. If I click on a program that hasn't been started from either, it takes an absurd amount of time to start it. And I get an error notification about it. Running a program with KRunner is okay though. The error is this:

> Starting: [App name]: Unsuccessful
> Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.

* The system tray also becomes unresponsive. If I scroll on the audio widget, it takes a big amount of time before I hear the sound has increased one step. Keyboard's "volume scroll" works fine though.

* Right click menus also... you get the idea. If I forget to ctrl+c / ctrl+v the thing I need to copy, then that file manager window freezes until the menu comes up.

Tested this on both Bazzite and OpenSUSE Tumbleweed. It happened on both systems so I'm sure it is not a distro issue. I'm not running out of memory either.

STEPS TO REPRODUCE
1. Log in to plasma
2. Use the system for a while
3. Try to do anything related to the bullet points above

OBSERVED RESULT
System is incredibly laggy to respond to my actions, and also gives out errors.

EXPECTED RESULT
System should not be laggy.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Bazzite latest, OpenSUSE Tumbleweed
KDE Plasma Version: 6.4.0-6.4.2
KDE Frameworks Version: 6.15.0
Qt Version: 6.9.1

SYSTEM SPECS:
AMD Ryzen 5 7600 CPU
AMD Radeon RX 7800 XT GPU
64 GB RAM

ADDITIONAL INFORMATION
N/A
Comment 1 Harald Sitter 2025-07-11 09:10:23 UTC
Please install https://flathub.org/apps/org.freedesktop.Bustle and record your session bus, try to open something to trigger the timeout, wait for the timeout, stop recording, save (ctrl-s), upload the saved pcap file.

Please also attach the output of 

journalctl -b 0 _SYSTEMD_USER_UNIT=dbus-broker.service

and

journalctl -b 0 _SYSTEMD_USER_UNIT=dbus-daemon.service
Comment 2 lesaysthismailisforbugzilla 2025-07-12 02:29:55 UTC
Created attachment 183174 [details]
Output of journalctl -b 0 _SYSTEMD_USER_UNIT=dbus-broker.service
Comment 3 lesaysthismailisforbugzilla 2025-07-12 02:32:29 UTC
(In reply to Harald Sitter from comment #1)
> Please install https://flathub.org/apps/org.freedesktop.Bustle and record
> your session bus, try to open something to trigger the timeout, wait for the
> timeout, stop recording, save (ctrl-s), upload the saved pcap file.

It fails to save the results as a pcap file with the console output below:

(bustle:2): GVFS-WARNING **: 05:27:40.211: The peer-to-peer connection failed: Permission denied. Falling back to the session bus. Your application is probably missing --filesystem=xdg-run/gvfsd privileges.

(bustle:2): GVFS-WARNING **: 05:27:40.211: The peer-to-peer connection failed: Permission denied. Falling back to the session bus. Your application is probably missing --filesystem=xdg-run/gvfsd privileges.

(bustle:2): GVFS-WARNING **: 05:27:40.219: The peer-to-peer connection failed: Permission denied. Falling back to the session bus. Your application is probably missing --filesystem=xdg-run/gvfsd privileges.

(bustle:2): GVFS-WARNING **: 05:27:40.220: The peer-to-peer connection failed: Permission denied. Falling back to the session bus. Your application is probably missing --filesystem=xdg-run/gvfsd privileges.

(bustle:2): GVFS-WARNING **: 05:27:40.220: The peer-to-peer connection failed: Permission denied. Falling back to the session bus. Your application is probably missing --filesystem=xdg-run/gvfsd privileges.

(bustle:2): GVFS-WARNING **: 05:27:40.220: The peer-to-peer connection failed: Permission denied. Falling back to the session bus. Your application is probably missing --filesystem=xdg-run/gvfsd privileges.

(bustle:2): GVFS-WARNING **: 05:27:40.220: The peer-to-peer connection failed: Permission denied. Falling back to the session bus. Your application is probably missing --filesystem=xdg-run/gvfsd privileges.
2025-07-12T02:27:43.621695Z ERROR bustle::window::imp: Could not save: Failed to save to file

Caused by:
    0: Failed to write packet
    1: Invalid field value: PcapPacket: incl_len > snap_len

> Please also attach the output of 
> 
> journalctl -b 0 _SYSTEMD_USER_UNIT=dbus-broker.service

Added that one as an attachment just now.

> and
> 
> journalctl -b 0 _SYSTEMD_USER_UNIT=dbus-daemon.service

This one just says "-- No entries --"
Comment 4 lesaysthismailisforbugzilla 2025-07-19 21:41:44 UTC
Created attachment 183351 [details]
Screenshot of the graph created by Bustle as I was removing one txt file (1/7)
Comment 5 lesaysthismailisforbugzilla 2025-07-19 21:41:56 UTC
Created attachment 183352 [details]
Screenshot of the graph created by Bustle as I was removing one txt file (2/7)
Comment 6 lesaysthismailisforbugzilla 2025-07-19 21:42:09 UTC
Created attachment 183353 [details]
Screenshot of the graph created by Bustle as I was removing one txt file (3/7)
Comment 7 lesaysthismailisforbugzilla 2025-07-19 21:42:20 UTC
Created attachment 183354 [details]
Screenshot of the graph created by Bustle as I was removing one txt file (4/7)
Comment 8 lesaysthismailisforbugzilla 2025-07-19 21:42:31 UTC
Created attachment 183355 [details]
Screenshot of the graph created by Bustle as I was removing one txt file (5/7)
Comment 9 lesaysthismailisforbugzilla 2025-07-19 21:42:43 UTC
Created attachment 183356 [details]
Screenshot of the graph created by Bustle as I was removing one txt file (6/7)
Comment 10 lesaysthismailisforbugzilla 2025-07-19 21:42:59 UTC
Created attachment 183357 [details]
Screenshot of the graph created by Bustle as I was removing one txt file (7/7)
Comment 11 lesaysthismailisforbugzilla 2025-07-19 21:44:21 UTC
Since I cannot send the pcap file, I (hopefully) did the second best thing.

This problem persists in 6.4.3 by the way.
Comment 12 Harald Sitter 2025-07-19 22:03:57 UTC
Nothing particularly sticking out. 

When this happens please open a terminal and run

killall -ABRT plasmashell

that should bring up the crash dialog from which you can get developer information (With debug symbols please!), that may give us a glimpse into what's going on inside plasma.
Comment 13 lesaysthismailisforbugzilla 2025-07-19 23:16:10 UTC
Created attachment 183362 [details]
Crash info from killall -ABRT plasmashell
Comment 14 lesaysthismailisforbugzilla 2025-07-19 23:17:08 UTC
Took me a while to download the debug symbols, but here it is!
Comment 15 Harald Sitter 2025-07-19 23:48:05 UTC
Seems to be idle :/

Have you tried with a new user already? Could be that something inside your profile messes things up.
Comment 16 lesaysthismailisforbugzilla 2025-07-20 17:33:00 UTC
(In reply to Harald Sitter from comment #15)
> Seems to be idle :/
> 
> Have you tried with a new user already? Could be that something inside your
> profile messes things up.

Just did a check. It happens on a brand new profile as well, sadly.

(But tbh I'm not that surprised considering I've switched distros previously just to see if the issue persists)
Comment 17 lesaysthismailisforbugzilla 2025-07-26 18:43:36 UTC
You know what's weird? In other cases the apps work just fine.

Like, say I downloaded a file, if I tell Firefox to open its folder, then Dolphin opens up instantly.

Or if I launch Dolphin from KRunner, it opens up instantly too.

But if I try to launch Dolphin from the menu/panel, it takes a long time and throws out that error, though it works fine afterwards.

And everything works fine again if I force restart plasmashell.
Comment 18 Harald Sitter 2025-07-28 08:53:32 UTC
Very strange. I am afraid I don't have any immediate ideas. So far it seems dbus is responsive and all threads on the process are also idle when this happens.

Maybe something is stuck on a systemd level. But then krunner would also be effected...
Comment 19 David Edmundson 2025-07-31 07:35:18 UTC
*** Bug 507670 has been marked as a duplicate of this bug. ***
Comment 20 Sagnik S. 2025-07-31 12:32:43 UTC
If you want me to do any further debugging when it happens, feel free to let me know
Comment 21 lesaysthismailisforbugzilla 2025-08-03 17:14:39 UTC
(In reply to Sagnik S. from comment #20)
> If you want me to do any further debugging when it happens, feel free to let
> me know

Hello there! I've just read up on your bug report. Surprised that it takes way longer for you. I wonder if "heavy system usage" accelerates this (I usually use Firefox heavily, like opening and closing hundreds of tabs and such).

As for your offer, I don't really know what I can ask from you, because I don't know what causes this exactly.

What I DO know that this has started happening on 6.4. I wonder if a change between 6.3 and 6.4 is causing this.
Comment 22 Sagnik S. 2025-08-03 17:19:07 UTC
Yes heavy usage might be a cause. I usually have about 400-600 tabs open across all browsers (😭) and I get a bunch of notifications from Discord/Slack etc. all the time.
Comment 23 Sagnik S. 2025-08-03 17:22:36 UTC
Apologies I misinterpreted your first reply, not sure why it takes longer for me then. Although recently, it has been taking a bit longer to crash, almost close to a day.
Comment 24 Nate Graham 2025-08-08 19:52:20 UTC
*** Bug 507992 has been marked as a duplicate of this bug. ***
Comment 25 Sagnik S. 2025-08-20 23:03:01 UTC
I am not sure if anything changed, but after the last update I did 2 days back, there have been no problems since.

Operating System: Fedora Linux 42
KDE Plasma Version: 6.4.4
KDE Frameworks Version: 6.17.0
Qt Version: 6.9.1
Kernel Version: 6.15.9-201.fc42.x86_64 (64-bit)
Graphics Platform: X11
Processors: 32 × AMD Ryzen 9 5950X 16-Core Processor
Memory: 128 GiB of RAM (125.7 GiB usable)
Graphics Processor: NVIDIA GeForce RTX 3060
Comment 26 lesaysthismailisforbugzilla 2025-08-23 21:45:48 UTC
(In reply to Sagnik S. from comment #25)
> I am not sure if anything changed, but after the last update I did 2 days
> back, there have been no problems since.

Similarly to you, after switching to 6.4.4 I cannot trigger the bug anymore. Not sure what changed either.
Comment 27 Sagnik S. 2025-08-24 01:13:06 UTC
I think I encountered it once yesterday, but the frequency is significantly lower now
Comment 28 f.kargl 2025-10-10 23:39:08 UTC
I'm not sure this is a new problem unfortunately. I've encountered similar issues in the past (not entirely sure when I first encountered them anymore, but it was _well_ before Plasma 6.4, might have even been Plasma 5). 
In fact, I've had this exact issue again just ~a week ago and I'm still on Plasma 6.3.6 (Debian testing). This recent episode was apparently triggered by installing a large batch of plasma / Qt lib updates. The interface laggyness/hang happened pretty consistently after that.
There has since been another large batch of plasma / Qt package updates in the last few days and I haven't been able to reproduce it since then (although I haven't used it that much since and now have another issue where plasmashell just crashes on login, so there's that).