Doesn´t Vsync limit the fps to the maximum hz of the monitor? I mean if your graphics card can create more fps than the monitor can display, switching off vsync will not make the monitor show the extra fps...
This is not that simple. Vsync tries to synchronize your monitor refresh rate with frames produced. Ideally it should not affect performance - but if your system fails to produce amount of frames locked -> it has to catch it up and sync again and again to produce this perfect 1 image per monitor refresh. You could have even 50% performance reduction at those times.
Also this syncing and catching up is an extra work.
Besides - (im no pro at this and might tell some wrong) - your desired refresh rate goes together with game-loop. Locked at 60fps -> game can read 60 inputs per second, while running @ 200fps it can read what ur doing 200 times per second. You kinda do not see this - but the game is (for this example) more then 3x times more "responsive". "Good games" have its time flying "independently" from fps so you do not see the game's time slowing down - just the frames (or speeding up - not like some crappy console ports thinking that 30fps or 60fps == 1 second)
When I first disabled vsync for COH - I instantly felt camera responsiveness going up. You may just try it up yourself - and see if it makes difference for you or not.