Bug 444686

Summary:	Wayland (?): Agenda view slows down when moving the mouse
Product:	[Applications] korganizer	Reporter:	Katalin Rebhan <me>
Component:	agendaview (weekview)	Assignee:	kdepim bugs <kdepim-bugs>
Status:	REOPENED ---
Severity:	normal	CC:	winter
Priority:	NOR
Version First Reported In:	6.3.3
Target Milestone:	---
Platform:	Gentoo Packages
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description Katalin Rebhan 2021-10-30 21:04:56 UTC

SUMMARY
On my 150% scaled display, moving the mouse over KOrganizer's agenda view makes it take noticeably long to update, most visible by the red line on the timeline that shows where the mouse is moving like the mouse was moved but delayed. It seems to process every mouse move event even if new ones have already come in which makes it take a long time to become responsive again if you moved the mouse around a lot.

The issue occurs similarly but way less severely when moving KOrganizer over to my 100% scaled display. There, just moving the mouse around makes it behave normally but dragging to select cells still has the same problem. (I'm assuming it's just not taking as long to redraw the window there so it's less noticeable.)

I put "Wayland (?)" in the title because I'm not exactly sure if this is Wayland-specific, I noticed it first when I switched to Wayland though and haven't tried X11 since.

STEPS TO REPRODUCE
1. (optional) Set display scale to 150%
2. Open agenda view
3. Move/drag mouse around on the table

OBSERVED RESULT
The UI slows down, taking longer to regain responsiveness the more you moved the mouse around.

EXPECTED RESULT
The UI stays responsive.

SOFTWARE/OS VERSIONS
Operating System: Gentoo 2.8
KDE Plasma Version: 5.23.80
KDE Frameworks Version: 5.88.0
Qt Version: 5.15.2
Kernel Version: 5.14.14-gentoo-dist (64-bit)
Graphics Platform: Wayland
Processors: 12 × AMD Ryzen 5 5600X 6-Core Processor
Memory: 23.4 GiB of RAM
Graphics Processor: Radeon RX Vega

ADDITIONAL INFORMATION
KOrganizer commit 7ab02ec

Comment 1 Allen Winter 2025-03-18 13:01:14 UTC

I'm closing this once since its ancient and I haven't seen any similar reports.
wayland support is greatly improved recently.

if the problem persists in new KOrganizer versions feel free to reopen.

Comment 2 Katalin Rebhan 2025-03-20 00:54:16 UTC

Still happens, but it seems improved at least since just moving the mouse doesn't do it anymore, dragging (vertically) on the agenda view still does though but there also I think it's much faster than before.

I believe the problem is that it redraws the interface for every mouse position event (that changes the selection?) instead of skipping redraws to only the one where the mouse currently is, and each of these takes much longer the larger the window size is.

In fact, this also happens with 100% scaling on my 4k monitor with the window maximized, so it doesn't have anything to do with the screen scale.