Witcher 3 definitely seemed to have reduced stuttering for me, which was good as I was using ini tweaks to crank grass and shadow draw distance beyond standard ultra. The leap wasn't ground breaking, but I found a general improved of increased minimum framerate and frame stability, so a more consistent performance on the lower end.
I'm not educated enough on why this is the case, but yeah. Just seems to more efficiently handle the data load and streaming. It's never perfect, and it's not ground breaking, but given the hundreds of hours I've poured into The Witcher 3 it was here I saw the clearest improvement.