As with all Java programs, the performance of the web applications in the Web Server is dependent on the heap management performed by the JVM. Balancing times and throughput is a challenge. For more information, read the performance documentation for the Java HotSpot virtual machine, which can be found at http://java.sun.com/docs/hotspot/index.html.
Specific documents of interest include “Tuning Garbage Collection with the 5.0 Java Virtual Machine” and “Ergonomics in the 5.0 Java Virtual Machine”.
JVM options can be specified in the Admin Console on the configuration's Java tab ⇒ JVM Settings sub tab. In the CLI, use the wadm commands set-jvm-prop and set-jvm-profiler-prop.