In order to speed up slow upgrades, experienced folk ([1](https://civicrm.stackexchange.com/questions/16425/how-can-i-monitor-the-progress-of-a-slow-upgrade) [2](https://civicrm.stackexchange.com/questions/16426/speeding-up-a-slow-upgrade)) recommend reducing the size of the database to facilitate testing. What is the best way to declutter the database?