What is the performance of OpenJDK versus the SUN JDK?
There is no OpenJDK performance penalty. It's pretty much the identical source base as Sun's (now Oracle's) Proprietary JDK. The only place I've noticed a degradation is in the display quality of text and graphics of SWING apps using OpenJDK 6 on Mac OSX. It links to the old X11 liraries like OpenOffice used too. I believe this is already fixed in OpenJDK 7.