https://bugs.freedesktop.org/show_bug.cgi?id=39202
--- Comment #23 from Siganderson dj_def@webmail.it 2011-08-16 04:07:27 PDT --- (In reply to comment #22)
vblank_mode=0 kwin --replace
I just did it and it has the same effect of turning off vsync from the kde desktop effects settings panel: the FPS doesn't go beyond 60/61 and vsync is actually disabled.
I'm going to bisect between 2.6.38 and 2.6.39-rc1.