Thank you very much for your response. Again, please do not see my questions as anything like criticism - MC is a pretty decent solution and I'm sticking with it. Next,
1. Tried turning it off in Core Settings as you said. Now it defaults to "Normal, Different disks". Better than what I had before but I'd really like the way to set it to "Normal, Same disk" because 99% of my file operations are performed on, well, one and the same disk C.
2. About testing: it's 6 minutes versus 15 minutes according to my wrist watch. Tested after reboot to make sure Windows built-in caching does not interfere. I don't think I'm imagining it. Test data is the Firefox profile directory - 500 MB of small files.
3. I found a workaround of enabling drive cache in the "Power, Same disk" strategy. Dirty but works.