I looked after the game and my CPU was hardly used at all so I'm limited by my graphics card which still gets over 60FPS.
*I NORMALLY play using RadeonPro to force VSYNC ON to eliminate tearing. My monitor supports 50Hz at 1920x1080 so I drop AF to 4x, force 2xAA then VSYNC at 50FPS.
I noticed that my 62FPS basically didn't waver which I've NEVER seen in any other game with VSYNC disabled. It made me wonder if the game engine was somehow artificially capping at that frame rate.
Anyway, try to get above 60FPS if possible and force VSYNC on with whatever tools NVidia uses for that.
Again, I suspect it's something to do with the game and not your hardware or software settings that are the issue.