Thanks! This was the first answer in 2 Ubuntu Forums and VMware Forum after a week or so.
You actually gave out relevant information for my tests: a) this IS supposed to be supported (Ubuntu 20.04.1). According to some Google threads, it was unclear and I did specifically ask about this support in my question, b) holiday season is the reason for no answers. Information that this combination IS supported would have helped.
I didn't say it was "slow". I said it is "very very slow and unusable". As a description of events, it is so slow that when selecting a username in Windows login, it doesn't seem to proceed at all.
Based on your answer, I will test with different BIOS setup combinations for virtualization. It's a bit cumbersome, because VM must be killed - no ordinary shutdown is possible because of the slowness - and thus VM can be broken at some point. I will test with Windows 7 VM, which I now use with Windows 10 Host on a (theoretically) identical workstation without any issues.
If I find nothing, I will give you a fresh vmware.log for analysis.
