Observation:
As the subject says:
I selected a few books and clicked Send to Device (my PEz)
some of the books did not have EPUB available, so Calibre asked if I wanted to convert (Yes).
11 conversions queued . I opened Jobs to look-see

As I watched, after each conversion the book was sent.
Then I watched it send the Metadata (this is a big file as there are
lots of books on my device) and watched it burn (waste) over a minute of process time that just got done after the next book finished.
Is this just the way it has to happen or could it be made to hold off on sending metadata until all queued Device jobs finish?