without vertical-sync a graphics card will get sent all the information it can take and simply wait untel the right time to send it to the screen. this speeds up over all preformance by giving the chip less of a chace to sit idle, however it will also eat more cpu cycles wich can cause the problems mentioned in that pic. granted a happy balince of number of frames rendered ahead can be found and gernealy causes no input-lag at the default value. disableing vertical-sync also degrades 3d quality sevearly, because of its imprecice will produce "screen-tearing", were you see a thin horisonal wave move through the 3d image almost as a wave does through the water. personaly, i say just leave v-sink on.