Optimize your phpBB database.
It is always recommended to keep our database tables optimized which can be done by using the phpMyAdmin tool that is available on the cPanel.
To perform the optimization, just login to cpanel >> database >> phpMyAdmin
Then select the database for whose tables you want to optimize.
Once you select the database it will list all the the tables in it if we want to optimize any particular table then just select that particular table else click on check all to select all the tables in the database and then from the drop-down menu choose Optimize table. This will execute the OPTIMIZE TABLE SQL query on the selected tables which will now be updated and optimized. You can repair the tables same way just by selecting Repair database from the drop down list.