I had never seen this until I got a laptop with Win10. Without a dedicated graphics card, certain GUI components of all programs are fuzzy, so I have assumed that is due to Win10 trying to scale items that are not already proportioned properly without the help of a GPU. Pop up windows for installations, etc. on several things do not rednder with sharp edges (not program specific).
Are you running sans GPU and is this consistent on specific components of S1?