Performance tuning of an Oracle database is still a big deal no matter which version you are using. If you are running an enterprise grade database then you cannot do without AWR and there is no question about it. Following is the list of key AWR reports you should be aware of:

• @?/rdbms/admin/awrrpt   => General usage

• @?/rdbms/admin/awrrpti  => Run for a specific RAC instance

• @?/rdbms/admin/awrgrpt  => Run for all RAC nodes

• @?/rdbms/admin/awrsqrpt => Run for a specific SQL_ID

• @?/rdbms/admin/spawrio  => AWR IO Intensity Report

The Automatic Workload Repository (AWR) collects, processes, and maintains performance statistics for the database. You have to use these reports routinely in order to diagnose and then troubleshoot the performance issues in the Oracle environment.

I hope it helps.