Doug Gault from Hotsos will be presenting a FREE webinar on May 28th: Performance Tuning APEX Applications.
From the Hotsos site:
Application Express (ApEx) is a highly flexible and highly scalable Rapid Application Development environment for web applications. But what do you do when your application's success starts to become its downfall? This free, one-hour presentation will cover strategies and tactical advice for monitoring and addressing performance issues, and presents some of the best practices for making ApEx Performance Problems easy to diagnose. This webinar is presented by Doug Gault, head of Hotsos Product Development.
No one that I know of does Oracle Performance Tuning like the folks at Hotsos do, so I'm sure that this presentation will be packed with tips and best practices.