The Cubase 10 UI seems much slower than Cubase 9.5.
I particularly notice it in the MIDI editor.Changing a note length or changing it’s pitch by dragging the note with the mouse is like moving through treacle.
Although I’m on Mac have Windows 8.1 installed on bootcamp and I just tested Cubase 10 I didn’t find any lag with the MIDI at all so it might be specifically a Windows 10 issue.