OS Level Zoom creating issues for CM

I have a user with non standard font and zoom level in his Win 7 setup. He’s complaining that moving the cursor takes a few seconds and editor is unusable. Wondering if anyone has seen this before?

Is this the ‘make it easier to read what’s on the screen’ feature under control panel -> display? I tried setting that to 125% (the only possible setting other than 100%), but CodeMirror still worked fine (in IE11 and Chrome).