kwin doesn't apply vsync when logging in. The vsync checkbox is enabled in System Settings and the setting is stored correctly in kwinrc:
The method used doesn't matter (automatic, only when cheap, etc.) In order to activate vsync after logging in, I have to open the desktop effects settings, and change any random setting (doesn't have to be the vsync checkbox, which is already checked) and then click "apply".
This problem did not occur with KDE 4.10.97. It started with 4.11.0 and also exists in 4.11.1. My ~/.kde4 directory was created by 4.10.97.
Steps to Reproduce:
1. Enable VSync in the Desktop Effects settings.
3. Login into KDE
Tearing when moving windows.
Tear-free animations due to VSync being enabled in the Desktop Effects settings.
X.Org server 1.14.2
NVidia driver 325.15 on a GTX 560 Ti
*** This bug has been marked as a duplicate of bug 322060 ***