Honestly, the only performance data involving Java, that would ever surprise me: is when a Java program takes less time to startup and get going, then the computer it is being run from did ;).
When planning-ahead for a project, I look at what performance the language implementations offer, in the light of "Blazingly fast on all but the extreme cases" or "Fast enough for the job, and still cycles leftover to toast bread with" like questions; the rest gets more specific to the problem domain. I have only ever had one main stream language prove to slow for my needs over the years, and that was because it was the least optimal use for perl... although I must admit, I would never want to try software rendering in pure Python (to what extent that is possible). -- http://mail.python.org/mailman/listinfo/python-list
