Just followed the Keynote at Jazoon: William O'Mullane talked about Gaia, the European Space Agency's astrometric platform, and why they mostly use Java for it. I mean, these guys are concerned about performance, right? Well, look at this slide:
Next time you're challenged about the topic, and can't give your own data because of e.g.customer confidentiality, you can refer to this talk (slides will be soon available at the Jazoon site).
Thanks to Mirko Stocke for the shot, I wasn't fast enough to take it.