Um artigo bastante interessante para os utilizadores de Oracle e PL/SQL, que se preocupam com questões de performance :

"Have you ever been frustrated with SQL Tuning?Did you get lost in the maze of /+ HINTS +/ and analysis paralysis?Pre-10g you have to be either a SQL tuning expert or should have a license to expensive tuning tools available in the market to effectively tune SQL Statements. Not the case anymore.
In 10g you can use DBMS_SQLTUNE package to get tuning recommendations for SQL Statements. "

Aqui http://www.orafaq.com/node/1837