Ouch.
“Parallels notes that these operating systems currently run "really slow" due to the overhead required for translation. Windows takes between two and seven minutes to boot, depending on the speed of your Mac, and "the responsiveness of the operating system is low." Rather than attempting to multi-task, Parallels says you should close the app you're using before trying to open another one.”
That’ll be because it’s emulating rather than virtualising, of course.
And it means that for the next few years, Parallels will be able to justify each new annual (chargeable) version because “Now it’s 80% faster” as they optimise the code
Makes me glad I dumped it a couple of years ago.