(I'm a new DBA, so please feel free to correct or comment)

Another point, depending on the # of rows in the table and the number of rows that you're deleting, an index may help or hurt the delete. This is something the optimizer might take care of, but you might check the explain plan to verify. Assuming that you already have an index on the selection criteria, e.g. client id or name, and that you're running in cost-based mode, if our selection criteria returns > 5-7% of the rows in the table, and by bulk delete I assume it does, the index may actually slow the delete.