Using triple buffering leads to stuttering of window contents while KWin effects remain smooth. The stutter can be observed both on my desktop using the NVIDIA blob and on my Ivy Bridge laptop using the free Intel driver. If I recall correctly, I observed similar issues on an AMD card but I can not test this anymore since I do not have the card anymore. Forcing double buffering with KWIN_TRIPLE_BUFFER=0 seems to fix the problems. Another workaround is to set MaxFPS and RefreshRate to 70. The problem affects both OpenGL with GLX and OpenGL ES using EGL. Steps to reproduce: 1. Start kwin_x11 with KWIN_TRIPLE_BUFFER=1 2. Start glxgears 3. Stutter should be visible In comparison, KWin shouldn't stutter when used with KWIN_TRIPLE_BUFFER=0 This website can be pretty useful to test for stuttering too: https://www.testufo.com/stutter#demo=smooth&foreground=ffffff&background=000000&pps=720 There are multiple other bug reports which might describe the same issue: https://bugs.kde.org/show_bug.cgi?id=381444 https://bugs.kde.org/show_bug.cgi?id=353038 https://bugs.kde.org/show_bug.cgi?id=344433 https://bugs.kde.org/show_bug.cgi?id=351700
Please provide output of qdbus org.kde.KWin /KWin supportInformation When the problem is visible.
https://paste.fedoraproject.org/paste/cZ9C9rGxJPsw0lHd6MtKYw/raw qdbus org.kde.KWin /KWin supportInformation
Got the same problem with an i5-3320M using internal graphics and official intel drivers (Fedora 26 with linux 4.13.9). drivers: cairo.i686 1.15.4-25.intel20171 cairo.x86_64 1.15.4-25.intel20171 cairo-gobject.i686 1.15.4-25.intel20171 cairo-gobject.x86_64 1.15.4-25.intel20171 intel-gpu-tools.x86_64 1:1.18-25.intel20171 intel-graphics-update-tool.x86_64 2.0.5-25.intel20171 intellinuxgraphics-repo.noarch 2.0.5-25.intel20171 libva-intel-driver.x86_64 1.8.0-25.intel20171 xorg-x11-drv-intel.x86_64 2.99.917-28.20160929.fc26 kwin-startup: OpenGL vendor string: Intel Open Source Technology Center OpenGL renderer string: Mesa DRI Intel(R) Ivybridge Mobile OpenGL version string: 4.2 (Core Profile) Mesa 17.2.2 OpenGL shading language version string: 4.20 Driver: Intel GPU class: IvyBridge OpenGL version: 4.2 GLSL version: 4.20 Mesa version: 17.2.2 Linux kernel version: 4.13.9 Requires strict binding: yes GLSL shaders: yes Texture NPOT support: yes Virtual Machine: no qdbus org.kde.KWin /KWin supportInformation: https://paste.fedoraproject.org/paste/kZtjEemRGVlc4PEkozVbMw/raw
*** This bug has been marked as a duplicate of bug 344433 ***