Did you get this:
http://gnubox.dyndns.org:8080/~sunil/knoppix.clean

Umm...don't run that on your Linux install. In fact I never make it executable until I put it into the remastering environment.

Did you do this:
deborphan | xargs apt-get -y remove

and this:
COLUMNS=200 dpkg -l |grep ^rc |awk '{print $2} ' | xargs dpkg -P

If you did all that then the only other thing that I know of is the sorting script which can be found on the mailing lists but I haven't really figured out how to use it. I don't think that would have anything to do with the size of your image however.

Also don't forget to remove anything you might have built in /usr/src but you probably did that already.