Removing accumulated waste.
WHAT ACCUMULATES
Post revisions, sometimes dozens per page Spam and trashed comments Deleted content still in the trash Orphaned data from removed plugins Expired temporary data Old log entries
WHAT THIS COSTS
A larger database is slower to query.
It also consumes disk, which matters if you are near a limit.
HOW TO CLEAN IT
An optimisation plugin, which does it safely with options.
Back up the database first. Always.
WHAT TO REMOVE SAFELY
Spam comments Trashed content you do not want Expired temporary data Old revisions beyond a few
WHAT TO BE CAREFUL WITH
Anything you are unsure about.
A plugin offering to remove "unused" data may remove something a plugin needs.
LIMITING REVISIONS GOING FORWARD
WordPress can be configured to keep only a few revisions per page.
That prevents the problem recurring.
HOW OFTEN
Quarterly is sufficient for most sites.