Bug 399041

Summary:	Qt 5.11.2 causes stuttering on the splash screen
Product:	[Plasma] plasmashell	Reporter:	Matthew Trescott <matthewtrescott>
Component:	Theme - Breeze	Assignee:	visual-design
Status:	RESOLVED DUPLICATE
Severity:	normal	CC:	chris, kde, nate, plasma-bugs
Priority:	NOR
Version:	5.13.5
Target Milestone:	1.0
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description Matthew Trescott 2018-09-25 02:04:27 UTC

SUMMARY
After upgrading to Qt 5.11.2 from 5.11.1, the splash screen's circular "loading" indicator stutters noticeably. Perhaps also related is that when closing Chromium, KWin's fade animation is not smooth. I'm not sure why this is. After I noticed this, I downgraded Qt to 5.11.1 and the problems went away.

Sorry to file this in such an obscure component. I suppose this bug will have to be forwarded to Qt but I wanted some help triaging it first.

STEPS TO REPRODUCE
1. Upgrade to Qt 5.11.2
2. Log out
3. Log back in

EXPECTED RESULT
The splash screen's "loading" indicator spins smoothly.

ACTUAL RESULT
The "loading" indicator freezes for brief moments while it spins.

SOFTWARE VERSIONS
(available in About System)
KDE Plasma Version: 5.13.5
KDE Frameworks Version: 5.50
Qt Version: 5.11.2

ADDITIONAL INFORMATION
This is a very normal system with Intel Haswell graphics and I am using X11 (not Wayland).

Comment 1 Kai Uwe Broulik 2018-09-25 07:35:08 UTC

Does this only affect the splash screen or also other places where a busy indicator is spinning, like a file copy?
Does this also happen when you run ksplashqml --test?
If you, can you provide the output of QSG_INFO=1 ksplashqml --test

Comment 2 Chris Raven 2018-09-25 11:28:08 UTC

I can confirm that this occurs to myself as well, the same way that Matthew has described. Running the test that was asked of Kal did not cause the issue.

Qt 5.11.2 (x86_64-little_endian-lp64 shared (dynamic) release build; by GCC 8.2.1 20180831) on "xcb" 
OS: Antergos Linux [linux version 4.18.9-arch1-1-ARCH]

That being said, I've had this issue on and off for a LONG time, and it does seem to be when it is reading from the HDD (Though I have an SSD and nothing else.

Comment 3 Nate Graham 2018-09-25 19:07:22 UTC

FWIW We have other reports of this happening elsewhere in Qt 5.11.2, so I very strongly suspect that this is an upstream Qt bug.

*** This bug has been marked as a duplicate of bug 399053 ***