If your browser uses a script-blocker, you may note a file named
'urlclassifier3.sqlite' in /home/knoppix/.mozilla/firefox/knoppix/

This file starts out at ~20mb and grows significantly over time. This growth
is unnecessary to the operation of the script-blocker, and can be rolled -back
by a compaction process referred-to as 'vacuuming'.

The easiest and most preferable way to achieve this is to add an SQLite Manager
to your browser and occasionally just perform a compaction of the urlclassifier,
using the convenient SQLite Manager gui.