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The performance of bulk operations depends on several factors, including whether the operation is internal or external to the database server.
The database server executes LOAD TABLE, UNLOAD TABLE, and UNLOAD statements. Paths to the files being written or read are relative to the database server. A LOAD TABLE statement is recorded in the transaction log as a single command. Internal importing and exporting only provides access to text and BCP formats, but it is a faster method.
Interactive SQL executes INPUT and OUTPUT commands. Paths to files being read or written are relative to Interactive SQL and the computer on which it is running, not to the server. An INPUT is recorded in the transaction log as a separate INSERT statement for each row read. As a result, INPUT is considerably slower than LOAD TABLE. This also means that INSERT triggers will fire during an INPUT. The OUTPUT statement is useful when compatibility is an issue since it can write out the result set of a SELECT statement to any one of a number of file formats.
For more information, see Performance tips for importing data.