Windows 10 performance slow on external monitor

Hello,
I am running Parallels 13 to run Windows 10 on my 2016 MacBook Pro. While the VM is running on the laptop everything is smooth, but when I attach my external monitor, the VM becomes laggy and has a lot of graphical artifacts, e.g. black boxes where a menu should be.

I did some research prior to posting, from what I read VM's do not utilize the graphics card so Windows 10 will never run smoothly when displayed on an external graphics card. Is this true?