Upgraded to Parallels Desktop 12 and installed MacOS Sierra. WOW! Screen redraw in Windows is slower than a herd of snails traveling through peanut butter. Guest was set to DX10. Tried DX9, no discernible change. Tried disabling DirectX and just a crumb better, now really really choppy screen redraws. Notice it the most when moving a window around in the guest OS, or if an app highlights rows on mouse hover, its like slow motion. Do not upgrade to Desktop 12 and MacOS Sierra until this gets sorted out. Its painfully slow. Was using Parallels Desktop 11, OS X El Capitan with Windows 10 Enterprise x64 as the guest OS on a Macbook Pro Retina 15 Late 2013. Almost everything worked great (built in iSight camera wasn't available in the guest OS).