Found this on this weblog: Random thoughts:
Turns out that it wasn’t Tomcat 5 that provided the 15-20ms/page performance. Instead, it was the JRockit 8 JVM that did the trick. I got the same performance with Tomcat 4, but switching to Sun JVM /w server settings increased the rendering time to about 40ms/page. Oh well.
I definitely must try this.