A compact can help speed up queries and as such should be performed regularly based on the nature of the database. When the ratio of number of records deleted to number of existing records is high, queries will get slower.

To avoid this effect on database that perform many deletes, it is best to perform a compact with the "Recreate address table" option regularly. A nice interval would be when about 70% of the data has been deleted, or at least once a year.