Tarsnap hangs for 8-9 minutes after restoring one file

[Tim McCormack <cortex@brainonfire.net>]

I recently had occasion to restore a 700 kB file from several archives.
The file was retrieved within seconds, but tarsnap continued to hold
open a connection to something in Amazon EC2 (I assume the tarsnap
service) for 8 to 9 minutes. What is it doing, and how can it be made
faster, besides killing the process once I see the file is retrieved?

This is the command I ran, multiple times:

sudo time tarsnap -C tmp/recover/$DATE -x -f $ARCHIVE home/timmc/.bash_history

I'm running tarsnap version 1.0.36.1 on Debian Linux 8.

 - Tim McCormack