As with all Java programs, the performance of the web applications in the Sun Java System Web Server is dependent on the heap management performed by the virtual machine (VM). There is a trade-off between pause times and throughput. A good place to start is by reading the performance documentation for the Java HotSpot virtual machine, which can be found at the following location:
Java VM options are specified using the JVMOPTIONS subelement of the JAVA element in server.xml. For more information, see the Sun Java System Web Server 6.1 SP9 Administrator’s Configuration File Reference.