The majority of general performance problems in ITDS can be attributed to the following two causes:
1) lack of regular DB2 maintenance
2) inefficient ldapsearch operations querying the server repeatedly
Before opening a Service Request for performance issues, please see the following technote and make sure that DB2 maintenance has been performed recently:
http://www.ibm.com/support/docview.wss?uid=swg21263999
For more information read this technote