AdvanceSCAN is using 7-Zip's zip compression library,
which can be tuned to be far & away better than zlib. (I
use 7-Zip regularly for my zip compression needs.
Giving the -tzip -mx -mpass=4 -mfb=255 switches to the
7-zip command-line, on average, is between 1% and 5%
better than, say, zip -9.)
Just an idea, for perhaps your next (or some one after
THAT =) version-level change.
Both of these are open-source & hosted at SF:
AdvanceSCAN is found at
7-Zip is at