Which Open Source Java Application Server is the fastest?
I have heard good things about Resin as well. It has been a while since I've used JBoss, but at the time (>5 years) it was excellent. Hopefully support is better now since it's more mature and Red Hat supported.
I heard that Glassfish is the fastest server if you scale up to a big environment. This does it by grizzly.
Here are some performance stats.