Hi! I finally upgraded my Windows 7 Pro VM to Windows 10 (which for some reason isn't Pro), and it's nearly unusable. It takes forever (like 10-20 minutes) before I can do anything on it after booting, and even then most windows are non responsive after any input for several minutes. I was using Parallels 16 and macOS Catalina when I did the update, and eventually I had Windows clear out the previous version to clear up some space. It hasn't improved. I updated my computer to macOS Big Sur, and it's still just awful. I currently have it set to use just one processor core. I'm running a 2017 MacBook Pro with 16GB RAM (3 assigned to Windows), a 3.1GHz Quad-Core i7, and Radeon Pro 560 (4GB) graphics. The entire time I've been looking through the forums and writing this post, I've been waiting for Windows to switch from Background settings to Lock Screen settings in the Settings panel and it still hasn't done it. Does anybody have any tips?
I'm also having the same issue with a brand new core i9 iMac, giving 8 cores to Windows 10 VM and it's freezing constantly. Unusable. It can't be hardware because macOS is snappy.
I've recently noticed this too - it seems incredibly sluggish until the GPU fans kick up, but until then plugged in or not, is like watching molasses. I'm running MacOS Catalina on a 2019 MacBook Pro w/ 64GB ram, so this shouldn't be an issue IMO. I'm not sure if this started after one of Apple's security updates or not TBH.
I have experienced very similar issues, as I didn't have anything important stored on my windows virtual machine (and also had a backup), I tried a fresh install of Win 10 on a new virtual machine, which does appear to have solved the problems.
I found this post, it may be or may not be related, but I'm going to try the sfc /scannow, chkdsk /r commands etc to see if perhaps that would resolve it. https://forum.parallels.com/threads/slow-parallels-14.345326/#post-845944
So to follow up, that actually did the trick for me as well it seems. But I still have issues with Firefox when visiting this page: https://docs.microsoft.com/en-us/dotnet/. I have a screen recording but it's too big to upload.