Progress is displayed as fast as possible, which can actually rate-limit your
I/O, depending on how fast your progress output file can flush. i.e. if you're
using a very slow terminal, rendering progress could actually throttle your
This rate-limits the progress display to every second. Perhaps this should be
tunable, but I'm keeping this patch simple for now.
Signed-off-by: Steven Noonan <firstname.lastname@example.org>