While there have been notable improvements in JVM design, the performance of Java-based technology continues to be a concern for organizations considering J2EE adoption. This presentation addresses these concerns by providing a comprehensive overview of Java performance issues. We begin by looking at the impact of hardware configuration and JVM tuning on J2EE performance. Then, after introducing a strategy for application-level performance analysis, we examine the performance impact of various Java coding idioms, the core classes within the J2SE SDK and commonly used design patterns. Lastly, we will look at the performance issues with respect to XML processing, servlet and JSP execution, EJBs and distributed computing.