OK, this is strange, maybe someone can clarify a bit...
I did a file move (using explorer, doing cut&paste) of a bunch of files.
The move was from one folder into another, inside the pool drive.
-> that was an instantaneous action , as expected.
A couple of minutes later, I moved the same files into another folder of the pool
-> this time, the whole bunch of 90+MBytes gets actually copied 
...both actions were done locally, only working with the pool drive.
What is going on here, I don't understand that kind of behavior ?
regards,
Fred