Cleaning up Firefox's data

My Firefox's profile data is really huge, I have two profiles, both are over 100MB. If I switch History tab on and try to search for something, it takes quite a time to get results.

Clear Data

Go to Tools/Clear History, I only choose Browser/Download History and Cache. Don't forget to choose time range to everything.

Delete urlclassifier*

Close all Firefox windows first. It's for blocking phishing sites. There are two files, urlclassifier3.sqlite and urlclassifierkey3.txt,
you can read more about it on MozillaZine Knowledge. (I didn't disable the features but deleted directly and didn't see any side effects.)

After you start Firefox, the file will be recreated but much smaller. However, it grows back quite fast.

Vacuum Databases

Close all Firefox windows first. If you use Linux, you can run the following command to do the job:

for fn in ~/.mozilla/firefox/*/*.sqlite ; do sqlite3 $fn vacuum ; done

Mozilla Link had a comparison before/after vacuum.