Nvidia driver problem...maybe?

What do you mean playing poorly that desn't tell us anything? Also need to know all your specs and what other games are you trying t play exactly?

LOL ok you have the same exact issue I do and the issue is as certain games don't perform well over 60 FPS because devs have nt coded the game to function at those high frame rates. Another thing is it shouldn't really matter how high your FPS is more how steady unless you're monitoring it you can't really notice the difference when it remains steady hence the purpose of v-sync.

Games (most especially FPS games) are often not optimized to run over 60 FPS assuming our tv/monitor can even handle certain levels of frame rates as well. Depending on whether you tv/monitor is interlaced or progressive your 60 or 120 or 240 Hz may be getting the full FPS convertion or only half. Although microstutter issues are extremely common in machines such as ours that are too strong for certain titles and their poor graphics. V-sync helps to try and keep it stable.

If there is a simple 10 FPS drop I wouldn't worry about thats totally normal in certain conditions of the game when the game eats up a lot of VRAM for the moment. This is common for me on Skyrim when loading a large area with many enemies my FPS may be at a steady 60 then dip for a moment as the video card attemts to catch up again.

I have a microstutter issue with MW3 because they still use the same poor old engine as the previous games since COD4 (MW1). FPS that rockets higher than 60 will cause microstutter and I admit its very game breaking when you cant aim! Although my Skyrim runs fantastic like 90-95% of the time. It's just during the high load times that it dips but I would take an occasional dip than a constant microstutter any day.

Anyhow you have a good PC and I would not be worried about it much. The last issue is YES it may very well be a driver issue involving how well it utilizes v-sync and its entirely possible that the driver may not be optimized to use v-sync as well as the last. Anyhow I hope some in this long essay is your answer. Nothing we can do but sit and wait or revert to a driver that has been known to run super smooth not sure how to help there LOL! Anyhow you're not alone!

P.S. If your screen ever flashes green, then black then picture gets restored and the audio is gone and it has a constant microstutter in any game. Take note that its not your GPU but the new driver don't be alarmed. Save your game then restart your PC and it should be gone. It made my heart almost sky rocket through my brain when it happened. But it's very rare that its the hardware just though I would let you know that!

Hope this helps further as well.
http://www.camcorderchris.com/back-to-basics-lesson-9-progressive-vs-interlaced-video-frames/