Bug 493376

Summary: Selecting many .desktop files on the desktop causes extreme lag
Product: [Plasma] plasmashell Reporter: alt
Component: Desktop icons & Folder View widgetAssignee: Plasma Bugs List <plasma-bugs-null>
Status: REOPENED ---    
Severity: minor CC: agarplayerarlon, aspotashev, hein, kdedev, madness742, nate, postix
Priority: NOR Keywords: efficiency-and-performance
Version First Reported In: 6.1.5   
Target Milestone: 1.0   
Platform: Manjaro   
OS: Linux   
See Also: https://bugs.kde.org/show_bug.cgi?id=388808
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: Video of the desktop lagging
Video showcase of the bug (230 desktop icons).

Description alt 2024-09-19 17:52:21 UTC
SUMMARY
Quickly selecting/deselecting multiple .desktop files on the desktop using the selection rectangle causes lag and throttling, especially if at least 10 (the minimum number may vary) are being selected in a row or column.

STEPS TO REPRODUCE
1. Add at least 10 different .desktop files (symlinks) from the application launcher by right-clicking on an each app and selecting "Add to Desktop".
2. Align all the files in one or multiple rows/columns on the desktop.
3. Hold the left mouse button and quickly move the cursor until they are all selected, then quickly move it backwards while still holding the button to deselect them one by one.
4. Repeat the previous point multiple times to cause lag.

OBSERVED RESULT
You should notice visible lag.
I also get this message from the system log: "systemd[1]: Looping too fast. Throttling execution a little."

EXPECTED RESULT
There should be no lag at all.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 
KDE Plasma Version: 6.1.5
KDE Frameworks Version: 6.5.0
Qt Version: 6.7.2
Kernel Version: 6.9.12-3-MANJARO (64-bit)
Graphics Platform: Wayland

ADDITIONAL INFORMATION

I'm using a hybrid graphics laptop (Intel + Nvidia).

Operating System: Manjaro Linux 
Processors: 12 × 13th Gen Intel® Core™ i5-13420H
Memory: 15,3 GiB of RAM
Graphics Processor: Mesa Intel® Graphics
Comment 1 alt 2024-09-19 17:56:25 UTC
This issue may be related to https://bugs.kde.org/show_bug.cgi?id=489894
Comment 2 alt 2024-09-19 18:07:53 UTC
(In reply to alt from comment #1)
> This issue may be related to https://bugs.kde.org/show_bug.cgi?id=489894

I was able to reproduce this bug too
Comment 3 Nate Graham 2024-09-19 18:54:31 UTC
Do any of the apps have large images set as their icons? If so, this is probably another manifestation of Bug 489894.
Comment 4 alt 2024-09-20 00:11:40 UTC
No, they are just ordinary icons, less than 100 kB
Comment 5 Nate Graham 2024-09-20 16:48:16 UTC
Hmm, OK. I can't reproduce it, unfortunately.
Comment 6 alt 2024-09-20 23:57:27 UTC
(In reply to Nate Graham from comment #5)
> Hmm, OK. I can't reproduce it, unfortunately.

I was able to reproduce it on a live USB of Manjaro, but I had to switch to a Wayland session because this issue doesn't happen with X11. I'll add a video as an attachment.
Comment 7 alt 2024-09-21 00:27:45 UTC
Created attachment 173927 [details]
Video of the desktop lagging
Comment 8 Nate Graham 2024-11-05 17:44:51 UTC
Does it still happen in Plasma 6.2?
Comment 9 alt 2024-11-08 08:46:18 UTC
(In reply to Nate Graham from comment #8)
> Does it still happen in Plasma 6.2?

Yes, still there
Comment 10 Nate Graham 2024-11-12 18:10:41 UTC
Can reproduce with over 100 icons on my system. Probably the threshold at which it starts to happen is dependent on the hardware, and maybe secondarily the contents or mimetypes of the icons.

Should be fixed with https://invent.kde.org/plasma/plasma-desktop/-/merge_requests/2628.
Comment 11 Akseli Lahtinen 2024-11-13 12:51:17 UTC
Git commit f7a92f7e65ac09cfd82a01835ac9f955c1b25744 by Akseli Lahtinen.
Committed on 13/11/2024 at 12:51.
Pushed by akselmo into branch 'master'.

FolderView: Performance improvements for selections

This MR has multiple changes, especially related to the "rubberband" (selection rectangle).

- Use `Qt.callLater` for `gridView.rectangleSelect` to eliminate redundant calls.
  - This was previously called *every time mouse moved one pixel*
- Clear a redundant mapToItem
  - `var cPos = mapToItem(gridView.contentItem, mouse.x, mouse.y);` needs to be only called during rubberband action
- Update dragItem images after selection is done, instead of every time a delegate is selected
- Instead of creating and destroying `selectionButton` in `FolderItemDelegate`, create it once and toggle its visibility


These all should help with the performance related to selecting multiple icons by dragging the selectiong rectangle around them.

M  +13   -17   containments/desktop/package/contents/ui/FolderItemDelegate.qml
M  +26   -9    containments/desktop/package/contents/ui/FolderView.qml
M  +5    -0    containments/desktop/plugins/folder/foldermodel.cpp
M  +1    -0    containments/desktop/plugins/folder/foldermodel.h

https://invent.kde.org/plasma/plasma-desktop/-/commit/f7a92f7e65ac09cfd82a01835ac9f955c1b25744
Comment 12 agarplayerarlon 2025-02-13 13:40:29 UTC
hey, this bug is still present in Plasma 6.3
Comment 13 Nate Graham 2025-02-13 15:11:34 UTC
In that case, it's actually Bug 469445. You can fix it yourself by deleting the `ScreenMapping` section in your `~/.config/plasma-org.kde.plasma.desktop-appletsrc` file and let it get regenerated naturally.

*** This bug has been marked as a duplicate of bug 469445 ***
Comment 14 alt 2025-02-13 17:18:00 UTC
I don't think this is a duplicate of bug 469445, as I have deleted the ScreenMapping section of  ~/.config/plasma-org.kde.plasma.desktop-appletsrc and the issue still persists (plus, I never had crashes, nor other slowdowns except this specific one). Moreover, as I pointed out previously in a comment, this bug doesn't happen while using X11, but only while using Wayland. So I think that this is a clear indicator that it must be something related exclusively to the Wayland-specific implementation.
Comment 15 TraceyC 2025-02-13 17:57:28 UTC
Re-opening since the issue is still occurring in 6.3.0, even after the workaround

FWIW I can't replicate this on git-master or 6.3.0 but as Nate said, it might be hardware dependent, using about 30 .desktop shortcuts
Comment 16 madness742 2026-01-11 05:46:44 UTC
I can reproduce this on Plasma 6.5.4. It's not as bad on my hardware, but still noticeable with a high refresh rate monitor.

Operating System: Fedora Linux 43
KDE Plasma Version: 6.5.4
KDE Frameworks Version: 6.21.0
Qt Version: 6.10.1
Kernel Version: 6.18.3-200.fc43.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 32 × AMD Ryzen 9 7950X3D 16-Core Processor
Memory: 64 GiB of RAM (62,4 GiB usable)
Graphics Processor: AMD Radeon RX 7900 XTX
Manufacturer: Micro-Star International Co., Ltd.
Product Name: MS-7D75
System Version: 1.0
Comment 17 agarplayerarlon 2026-01-15 13:17:51 UTC
this doesn't seem to happen anymore in kde plasma 6.5.5, or at least it happens way less and is way less noticeable.
I think what might have improved this situation here is the commits related to bug 508684 https://bugs.kde.org/show_bug.cgi?id=508684
Comment 18 madness742 2026-01-15 15:46:09 UTC
(In reply to agarplayerarlon from comment #17)
> this doesn't seem to happen anymore in kde plasma 6.5.5, or at least it
> happens way less and is way less noticeable.
> I think what might have improved this situation here is the commits related
> to bug 508684 https://bugs.kde.org/show_bug.cgi?id=508684

I can still reproduce this bug with my machine on Plasma 6.5.5.
Comment 19 agarplayerarlon 2026-01-15 15:49:35 UTC
(In reply to madness742 from comment #18)
> I can still reproduce this bug with my machine on Plasma 6.5.5.

does it look the same or is it less noticeable?
Comment 20 madness742 2026-01-15 15:57:27 UTC
(In reply to agarplayerarlon from comment #19)
> does it look the same or is it less noticeable?

It looks the same.
Comment 21 Nate Graham 2026-07-29 20:11:41 UTC
madness742, can you provide precise instructions for how to reproduce it?

e.g.:
- Which desktop icons and how many
- Refresh rate of your mouse
- Refresh rate of your monitor
- Resolution and scale factor of your monitor

Also, can you do a bit of troubleshooting about how the problem changes if you change any of those variables?
Comment 22 alt 2026-07-30 14:17:59 UTC
I’m now running Plasma 6.7.3, and the issue appears to be resolved—the lag is gone. I tested it with over 40 .desktop files at both 60 Hz and 144 Hz, using scale factors of 100% and 110% at a resolution of 1920×1080.
Comment 23 Nate Graham 2026-07-30 14:21:20 UTC
Great news! Thanks for letting us know.

madness742, is that the case for you as well?
Comment 24 agarplayerarlon 2026-07-30 14:52:59 UTC
this is still happening to me, I'm seeing a lag when I select multiple desktop icons, but after selecting them it goes back to normal
Comment 25 Nate Graham 2026-07-30 15:58:30 UTC
On which version of Plasma? And please see Comment 21. We need more information about the circumstances under which the issue happens, since clearly it's not a universal issue that affects everyone.
Comment 26 agarplayerarlon 2026-07-30 22:46:17 UTC
(In reply to Nate Graham from comment #25)
> On which version of Plasma? And please see Comment 21. We need more
> information about the circumstances under which the issue happens, since
> clearly it's not a universal issue that affects everyone.

I'm using Plasma 6.7.3 on Fedora 44 KDE, on a 1080p screen with 100% scaling and a 144hz monitor and using Wayland.
I have 35 desktop icons with two rows of desktop icons, and when I select them all by dragging the square selection with the mouse left click, I see a lag when it starts selecting multiple desktop icons, and it's especially noticeable when it selects icons with a 1 line name after selecting icons with 2 lines name
Comment 27 Nate Graham 2026-07-31 13:23:37 UTC
Ok. See Comment 21; please do a bit of troubleshooting to figure out which of the possible variables at play are causing the issue.
Comment 28 agarplayerarlon 2026-07-31 15:29:08 UTC
after more testing I've found out that for me the icon that was causing the lag was the RPCS3 icon, which was using a PNG image that I've found on google, after regenerating the desktop entry from the RPCS3 app itself now there isn't any lag anymore, so the problem seems to be related to desktop icons that use custom images downloaded from the web, the custom icon I was using weights 5mb, so maybe that's the problem
Comment 29 madness742 2026-08-01 00:32:09 UTC
(In reply to Nate Graham from comment #21)
> madness742, can you provide precise instructions for how to reproduce it?
I'm able to reproduce this problem by following the steps mentioned in the bug report. However, I do not see the message in my system logs.
> e.g.:
> - Which desktop icons and how many
At around 10 desktop icons (symlinks) I start to notice degraded performance, the more desktop icons I add, the worse it becomes.
> - Refresh rate of your mouse
Polling rate of mouse (125Hz, 500Hz and 1000Hz) makes no difference.
> - Refresh rate of your monitor
144Hz.
> - Resolution and scale factor of your monitor
Main monitor is set to 2560x1440 with 100% scaling. Lowering the resolution to 1600x900 improves the performance by quite a bit. Connecting a second monitor (3840x2160) doesn't make the problem worse. Neither does increasing the scaling on the primary monitor.
> Also, can you do a bit of troubleshooting about how the problem changes if
> you change any of those variables?
I've also tested large icons (60 mb), as mentioned by Comment 28, and it doesn't seem to be causing a bigger performance hit compared to smaller icon sizes. This was tested with 17 desktop icons.

Operating System: Fedora Linux 44
KDE Plasma Version: 6.7.3
KDE Frameworks Version: 6.28.0
Qt Version: 6.11.1
Kernel Version: 7.1.4-200.fc44.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 32 × AMD Ryzen 9 7950X3D 16-Core Processor
Memory: 64 GiB of RAM (61,9 GiB usable)
Graphics Processor 1: AMD Radeon RX 7900 XTX
Graphics Processor 2: AMD Ryzen 9 7950X3D 16-Core Processor
Manufacturer: Micro-Star International Co., Ltd.
Product Name: MS-7D75
System Version: 1.0
Comment 30 madness742 2026-08-01 00:33:36 UTC
Created attachment 194760 [details]
Video showcase of the bug (230 desktop icons).