Compact and Repair a Microsoft Access Database
The reasons for the need to compact and repair Access databases can be found in the help files under Compact and Repair. However, many people don't know about it or don't realize its importance. A newly created database can easily become over a megabyte in size even without data. It is very important to run compact and repair as often as possible.
Depending on the number of transactions, you will ideally run compact and repair once per day.
Most databases should have Compact on Exit set. Go to Tools Options, General tab to "compact on exit".
In a multi-user database, compact occurs when the last user exits the database.
Compacting the database is especially helpful prior to emailing it.