Magento stores old sales quotes dating back to the first day you launched your site. Sooner than you know it, you can be up to a couple million quotes that have never been processed but which can take up significant space, and slow your database.
This SQL query will clean out quotes (and their related content in other tables) that are older than 60 days.
DELETE FROM quote WHERE updated_at < DATE_SUB(Now(),INTERVAL 60 DAY)
Make sure to get this task setup on a cron job so that you don’t have to think about it again and your Magento store can keep running fast!