Sorry for the lack of response on this one, it looks like it didn't actually get passed on as a bug.

The Outline Cursor is rendered directly on to the canvas surface and as we don't use GPU acceleration a different GPU won't fix the issue. As we don't use Windows scaling values, if changing Windows text scaling is making a difference then it may be because the OS is doing something with its scaling that's exacerbating a refresh rate problem. I'll look in to it!