Bug 393895

Summary:	Excessively long entries in plasma-org.kde.plasma.desktop-appletsrc can make the whole desktop feel slow and laggy
Product:	[Plasma] plasmashell	Reporter:	Nate Graham <nate>
Component:	general	Assignee:	David Edmundson <kde>
Status:	RESOLVED WORKSFORME
Severity:	normal	CC:	plasma-bugs
Priority:	NOR
Version:	5.12.5
Target Milestone:	1.0
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed In:
Attachments:	File with garbage in it

Description Nate Graham 2018-05-06 02:51:05 UTC

Created attachment 112433 [details]
File with garbage in it

I upgraded my main machine to Kubuntu 18.04 and was greeted with inexplicable slowness, lag, and application choppiness. Animations dropped frames, scrolling was laggy, and cursor movement seemed low-resolution. However, CPU usage was normal and KWin reported 40 FPS. In the end, the problem was found in the entry for my pinned virtualbox launcher in ~/.config/plasma-org.kde.plasma.desktop-appletsrc, which was 9600 characters long. Removing the pinned launcher fixed the issue.

This is mostly a downstream bug (https://bugs.launchpad.net/ubuntu/+source/virtualbox/+bug/1769417), but having an excessively long entry in that file shouldn't slow down the whole desktop.


Steps to Reproduce:
1. Install Kubuntu 18.04with Plasma 5.12.4
2. Install Virtualbox
3. Open Virtualbox
4. Right-click on its Task Manager entry and pin it (I'm using an Icons-Only Task Manager, if that makes a difference)

Garbage has been written to ~/.config/plasma-org.kde.plasma.desktop-appletsrc (attached, see line 98).

When the file has garbage in it like this, all of Plasma starts to feel slow and laggy. If I unpin the icon and thereby remove the garbage line, Plasma feels snappy once more.

Comment 1 Nate Graham 2018-05-23 14:05:13 UTC

Can't repo anymore; I think this was a matter of coincidence and pointer input issues with libinput from a buggy git master master version that I was using at the time.