You could check the June 9, 2003 issue of InfoWorld, page 48. There's a comparison of features, etc. related to web services. Unfortunately, I don't think they discuss performance too much.
Check theserverside.com. They had something recently about it.
I saw that link a couple days ago and it was invalid. I'll bet it was yanked.
BEA has always offered to sue anybody who publishes performance data on their server - we can't even post perf data for our products that ship on Weblogic.