Like others I had been having terrible performance problems like very slow boot times, black screens, task manager taking forever to load as well as slow apps, etc.. In browsing various posts here on the same or similar problems, I found one by a Parallels tech that worked miracles for me. In configuration/CPU and Memory/Advanced Settings change hypervisor from Parallels(default) to Apple. It worked wonders in my case at least. I also had disabled "fast load" in windows control panel, but that alone had no apparent effect.
