You say JBoss is slow in Windows 2000 have you tried using any other operating systems?
What does your test.jsp page actually do?
Are you using the Jetty or Tomcat version of JBoss 3.0.8.
Which JVM are you using?
Have you tried using servlet containers that aren't embeded into JBoss?
Are you sure that your load testing is working correctly? as you are using Windows 2000 have you considered installing IIS and running a test against a test.asp page so that you have something to compare with?
Are your users on the same machine as JBoss or are remote network calls involved?
We have the same problem with JSP compiles (and some MBean calls it appears) on Windows using the Sun JVM (build 1.4.2-b28)
After the first compile, request times are ok, but the compilation can take up to 60s. On linux with the same JVM build, there are no problems. It looks like there is a ton of startup time invoking javac, but that would not explain the MBean call problems.