Rythmer

What you're describing kind of sounds like a driver issue or a Video RAM issue. What is your current hardware at, if I can ask? Also, V-sync and Gsync are two completely different technologies even though their names sound similar. If your monitor has Gsync capability and is enable, it seems this can cause adverse performance if the game's V-sync is also enabled.

Good Find. What refresh rate is your monitor? I'm wondering, if I disable vsync and enable Gsync, if the physics will get all crazy since my monitor is 144Hz and my FPS will be well above 60fps.

funny turning it off worked for you - cranking it up worked for me. Yeah, interesting. The only thing I did was turn off Gsync. Everything else I left to auto-detect. (Ultra). However, I don't remember what my current graphics driver version is. I imagine that's a major factor as well.

I had the same issue while headed to Riverwood. I'm not sure if it's coincidence, but I saved and exited and then turned OFF G-Sync on my monitor. Opened the game and haven't had a single stutter since. Smooth as butter. Specs: GTX 980 Ti 27" ASUS ROG swift 144Hz. / Gsync i7 4770K 16GB Gskill Trident. Hope this helps someone.