Slowing down filewalker

This is true, partially. Unfortunately, as shown by many SNOs, who uses a pass thru drives to VM, this works not so good as expected, sometimes only 30% of the possible performance for some reason.
So I would assume, that pass thru (under Linux specifically) not so efficient.

I would suggest to test each case separately to help advanced SNOs in the future.

I tested under Windows - it works pretty well (no issues so far, include Hyper-V VM and WSL2, used only “shared folders” features, no pass thru). Tested also under Linux (KVM), but results were… confusing. My system has a hardware issue, incompatible with Linux, unfortunately (if someone interested - Moving from Windows to Ubuntu and back).