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).
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
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.
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 ***