System Settings becomes extremely laggy when opening “Notifications” panel

Help
1

I recently updated to KDE Plasma 6.4.5 (from 6.4.3) and noticed something strange:
whenever I open the Notifications page in System Settings, the whole window becomes very laggy and almost unresponsive until I switch to another panel.

While the Notifications panel is open, the systemsettings process CPU usage jumps to 100% on one core.
All other settings pages work completely fine.

I have tried:

  • Restarting System Settings
  • Testing multiple times (issue is reproducible every time)
  • Checking CPU usage via system monitor
  • Confirmed that only the Notifications panel is affected (other panels are fine)
  • Create a new user on my system and test again, but still

Here is a picture shows systemsettings app cpu usage when notifications panel opend:

图片
图片1920×1092 226 KB

When opening other panels…

图片
图片1920×1092 223 KB

Additional information

  1. Additionally, if I launch System Settings from the terminal (systemsettings) and then open the Notifications panel, it repeatedly prints messages like this every few seconds:

    qrc:/qt/qml/org/kde/kirigami/layouts/FormLayout.qml:132:5: QML GridLayout: possible QQuickItem::polish() loop
qrc:/qt/qml/org/kde/kirigami/layouts/FormLayout.qml:132:5: QML GridLayout: GridLayout called polish() inside updatePolish() of GridLayout

    These two lines keep appearing over and over while the Notifications panel is open.

  2. Before updating to Plasma 6.4.5, I was using Plasma 6.4.3 and this issue did not happen.
    I created a Btrfs snapshot before upgrading, and after restoring the snapshot (going back to 6.4.3), the problem disappears.
    So it seems to be a regression introduced in 6.4.5.

  3. The below text is my system information:

Operating System: Fedora Linux 42
KDE Plasma Version: 6.4.5
KDE Frameworks Version: 6.19.0
Qt Version: 6.9.2
Kernel Version: 6.13.12-200.fc41.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 8 × Intel® Core™ i5-10210U CPU @ 1.60GHz
Memory: 16 GiB of RAM (15.4 GiB usable)
Graphics Processor 1: Intel® UHD Graphics
Graphics Processor 2: NVIDIA GeForce MX350
Manufacturer: LENOVO
Product Name: 82DN
System Version: Lenovo XiaoXinPro-13IML 2020
2

This appears to be a language-specific issue. I can’t reproduce it with English, but LANGUAGE=zh_CN systemsettings kcm_notifications makes the issue appear immediately. Can you open a bug report about this on https://bugs.kde.org? Put it under the “frameworks-kirigami” product.

Thanks a lot!

3

Side note: I think it’s likely that a KDE Framework change triggered this, rather than a KDE Plasma change. Did your old snapshot contain Frameworks 6.18?

4

Ok, I tried creating a bug report at https://bugs.kde.org/show_bug.cgi?id=510758

By the way, I checked the packages in my snapshot and it mentioned that the KDE Framework version is 6.16.0