Database Tuning is outside of the scope of the Jazz Administrator. Any information contained below is for reference only and should be passed on to your database administrator.
Your DBA should enable row versioning, if it is not already enabled. Steps to do so can be found here: Enable Row Versioning. In particular, the READ_COMMITTED_SNAPSHOT setting should be turned ON.
Database tuning information can be found here: Tuning the Physical Database Design There are subsections that should be reviewed. In particular, there is a section on the Database Engine Tuning Advisor which will help in understanding whether additional indexes need to be added to your databases.