Make sure that W10 hasn't decided for you the driver(s) it want's you to have as opposed to the one(s) you want. That's the one and only reason why I won't switch over to W10. I very much dis-like the idea of someone at MS deciding for me the driver(s) I want and know I want. There is too much Automatic *** with W10. They like to tell people what a good OS it is but for some reason they don't think the person(s) that buy their O.S. is smart enough to decide for themselves what they want and need.
Come on MS get with the program people are not as dumb as you make us out to be, that we need your OS automatically doing things for us behind our backs.
One more question. What monitor ( exact brand and model and resolution), what kind of video cable ( DVI/HDMI/DP ?). the video cable probably doesn't matter of Valley and Cinebench looked good.
I'm still guessing at this point, and going from memory because right now I'm on a Win7 non gaming system and don't have the screens to look at...
If you go into the nVidia control panel, can you find the game listed and the settings used for the game?
I vaguely remember there is a choice to use global settings, or to adjust settings per program. If you override the gaming settings, can you dial back the eye-candy?
Things like Anti-aliasing, shader quality, shadow quality, textures etc. Dial them way back and see if the stuttering improves.