Having played about with more I've come to the same conclusion. It does feel like it made a difference, but I'm not sure if I'm just wilfully imagining that now. It's certainly not fixed, either way.
I went back and tried Zbrush on my old Surface Pro 2, this is one of the old Pro 2s, when they still had a Wacom screen. I've used that machine professionally and shipped assets made on it. Using it again after the Windows update it now has the same issue
as the Surface Book 2. It's still got Zbrush 4R7 on there, so I'm laying the blame solely at the feet of MS for this.
What's even more annoying is if I plug my trusty old Intuos in that works flawlessly. :/
I've made a ticket with Pixologic too, just in case they have any thoughts, but imagine a fix is out of their hands.
Does this mean anyone using a tablet/touch screen device is having the same issue now?