There is an ITIM Tuning Guide for each version of the product. They are updated periodically (roughly every 6 months) so it's a good idea to check to see if a new version is available.
In addition, a document with performance best practices for using the ITIM API is available:
A set of performance tuning scripts that often come in handy for finding unindexed LDAP queries or slow-performing DB2 queries, among other things, are also available:
