Some mental gymnastic is required to figure out the relation between this, "Low frame rate in fullscreen mode" and NoGDIHWAcceleration
https://www.gog.com/forum/general/ddrawcompat_yet_another_directdraw_wrapper/page1
https://sourceforge.net/p/dxwnd/discussion/general/thread/b8aaa6ff/#d506
https://github.com/narzoul/DDrawCompat/issues/28