Kindly reported by our great customer Matt @University of New England:

I used my Wacom Cintiq tablet mostly for segmenting, and the lag issue occurred at the initial touch of the pen on the screen.
Searching the Web, however, I found a site that explained how to fix this for tablets on Windows systems, mostly related to Photoshop users.
I followed most of these fixes in Windows Settings for the tablet. Unchecking “Use Windows Ink” in particular seemed to fix the issue.