Inner workings of 'copy' - is the server queried for each file?

Hmm, yes that is a bit of inefficiency to do with rclone looking to see whether you were looking for a file or a directory

When you do

rclone copy secret:object

rclone had to work out whether object i a file or a directory. It is doing this in an inefficient way at the moment by recreating the Fs. If you make an issue I’ll look at fixing it.