To improve performance, reduce the number of log events generated by the Integration Service when it runs the session. If a session contains a large number of transformation errors, and you do not need to correct them, set the session tracing level to Terse. At this tracing level, the Integration Service does not write error messages or row-level information for reject data.
If you need to debug the mapping and you set the tracing level to Verbose, you may experience significant performance degradation when you run the session. Do not use Verbose tracing when you tune performance.