Well, I do know that patch v1.31 pretty much destroyed the performance of the game for a lot of people, including me. Patch v1.10 was constant 40 fps locked to me, v1.11 made the game unplayable, literally, and v1.31 introduced major stuttering anywhere on the game, I tried all tweaks I could, but nothing. I barely hit 30 fps, with drops to 25 fps, often and with stutter.
But here are a few things you can do: Go to My Documents/Witcher 3 and delete user.settings and user.settings.bak, then adjust your settings again from scratch, every update, for some reason, breakes your settings, so you have to do this step each time a new game patch comes out.
Set V-Sync to Adaptive on nVidia control panel, then force it on, disable it in game. Set fps to unlimited, download MSI Afterburner+RivaTuner, they come together. Hope you are familar with this program, if not, tell me and I will explain it to you. Anyway, open up RivaTuner, hit the "+" icon below all executables, find Witcher 3 .exe location on your computer, click it, then search on the executables of RivaTuner, set a desired frame rate limit, in your case, 60 fps, then click "Vector3D" and then "Framebuffer". With this program you can control the fps limit of any game on the fly and the best thing is that often it eliminates the micro stutter in many games.
Here is how to use it even further:
https://www.youtube.com/watch?v=4yeROJQR_qE&t=262s (Watch the full video).
Finally, go to Witcher 3/bin/config/base/resources.ini (backup this file first so if you run into any issue, you can revert them quickly). Change the following:
FileQueueSizeGame = 100
FileQueueSizeLoading = 500
MaxRequests = 32
MaxCompressedBudget = 30
MaxUncmpressedBudget = 70
Change them to:
FileQueueSizeGame = 250
FileQueueSizeLoading = 700
MaxRequests = 45
MaxCompressedBudget = 10
MaxUncmpressedBudget = 240
That is said to help but then you can increase the values to this: (Try with the earlier value chance tweak first, if the stutter or the fps drops persist, try these then)
FileQueueSizeGame = 400
FileQueueSizeLoading = 850
MaxUncmpressedBudget = 500