One interesting thing I noticed today (did some tests as I today updated to the latest nvidia drivers) is that the game has more stutters for me with vsync ON. With vsync off, the stutters are almost gone, with the price of some tearing.
I always expected vsync on would smooth things out, doesn`t seem to be the case on my system.
Your right, I was able to turn everything back to HIGH @1920x1080 when I turned OFF vsync. Its was definitely one of the main culprits for micro stutters on my system.
That's because that is how v-sync works.
It forces the render buffer to only output when it has completed a frame, so if it misses a monitor sync cycle, it has to wait for the next.
IE., if your monitor is running at 60hz, with v-sync on, you will be effectively viewing only 60fps exactly...or 30fps (if it drops even 1fps below 60), 15fps, etc.
That's why nVidia created "Adaptive V-Sync" in their new drivers
. If you are rendering at higher than 60fps...it turns on v-sync, so you have a nice, solid 60fps display. If the render speed drops BELOW 60fps, it turns off v-sync so you don't experience the sharp drop to the next lowest 'synched' framerate.