At this year's devoxx you can visit my benerator tool demo. It takes place in Antwerpen at the 9th of December, 17:25-17:55.
See http://www.devoxx.com/display/JV08/Creating+performance+test+data+with+the+benerator for more information.
I will also tell about Hibernate performance tuning: http://devoxx.com/display/JV08/Hibernate+Performance+Tuning
