Hey,
I have a high-end high-DPI Windows 10 laptop with NVIDIA GeForce 940MX. DPI scaling is enabled system-wide. The display is 3840 x 2160. Scaling factor is 175%.
After installing Rhino 6 (6.1.18037.13441), I noticed that moving any objects through mouse drag-and-drop in a viewport is sluggish and choppy. This is true even if the only object is a rectangle and all viewports are set to wireframe, antialiasing is disabled, etc.
I don’t think this is a card / system performance issue, because rotating a scene by holding the middle button is extremely responsive and smooth.
Through trial and error, I noticed that finding rhino.exe and then going to Properties → Compatibility in Explorer, checking Override high DPI scaling behavior, and selecting System from the drop-down fixes the issue entirely, although it makes all text, including command prompt, look ugly and blurry. Setting this to Application restores the correct appearance but keeps the drag-and-drop slow.