Are you benchmarking with the Server or Client VM?
Also it's a shame that Apple hasn't updated the Java developer libraries yet.
Here are some benchmarks that I normally run to gauge java performance on different platform. I normally deal with numerical apps, so these are representative of the performance I can expect to get from Java in these situations.
Check out Scimark at
http://math.nist.gov/scimark2/run.html and Linpack at
http://www.netlib.org/benchmark/linpackjava/. Java's performance on OS X is still pretty dismal.
