Curious why vsync on, severely hinders performance?

[Victor B. Gonzalez]

My monitor supports 60 FPS. The Nvidia binary is pretty flawless if I disable 
vsync (albiet the tearing) but enabling vsync in effects makes everything look 
terrible, choppy and effects go down the drain. 

It's really a simple switch. Vsync off and everything is near perfect. Vsync 
on and everything goes to hell somewhat. Could this really be a driver bug and 
am I the only one experiencing it?

On Tuesday, August 14, 2012 02:35:09 AM Kevin Kofler wrote:
> Victor B. Gonzalez wrote:
> > I got the Nvidia binary 304.32 on KDE 4.9.00 on Fedora 17. KDE desktop
> > effects run pretty flawless at 100+ FPS no matter what I do **but** the
> > second I enable vsync on in desktop effect settings, FPS can drop to a
> > choppy 30FPS. Why does this happen?
> > 
> > Not a solid 30 FPS but a choppy 30 FPS.
> 
> Limiting the framerate to ~30 FPS (i.e. what your screen can actually
> display) is exactly what vsync is for. Now why it's choppy, I don't know. It
> might be that the effects are not syncing with vsync, so the FPS varies
> depending on when vsync hits compared to what the rendering thread is
> doing, or it might just simply be a driver bug (proprietary drivers are
> always very buggy, try Nouveau!). (It could be a combination, like the
> driver failing to tell clients such as KWin that vsync is in use, which
> would of course be a driver bug.)
> 
>         Kevin Kofler
> 
> _______________________________________________
> kde mailing list
> kde at lists.fedoraproject.org
> https://admin.fedoraproject.org/mailman/listinfo/kde
> New to KDE4? - get help from http://userbase.kde.org
-- 
Best Regards
Victor B. Gonzalez