Rated 2 out of 5 stars

REINDEX is useless. SQlite automatically reindexes entries, so unless you change the structure, you shouldn't execute that command.
VACUUM is done automatically by Firefox from version 3.6. But if you really want to do it more often, you can use an extension offering only the VACUUM command.

This review is for a previous version of the add-on (0.7.5).