Which should turn up the following link: http://www.ibm.com/developerworks/java/jdk/linux/download.html

You want to download “Java SE Version 6″ for the platform called “64-bit AMD/Opteron/EM64T” to get a JDK that runs on a 64bit x86 Linux with support for compressed references.

As for Scimark – this benchmark doesn’t have the same recognition as those that are hosted by http://www.spec.org/. However, looking at the Scimark results here http://math.nist.gov/cgi-bin/ScimarkSummary you will see that the top results are Sun based numbers, but a more careful look shows a nearly 1:1 correlation between CPU frequency and the score.

The Scimark results attributed to the IBM JDK don’t look “way slower” than those posted by the Sun JDK. Today the results ranked 4th and 5th compare the IBM and Sun JDK both on 3.0GHz CPUs and they are neck and neck.

Several years ago IBM’s java was the fast one for numeric work, but Sun’s java6
(64bit) is a fair amount faster than the 32bit Java6 (either IBM’s or Sun’s)
on the Scimark benchmark.