Rick,
there's an IBM java VM with jit. Much faster than the stock
Blackdown port.
Surf the list for "IBM" and "java" to see caveats. At this stage, you'll
need an SMP
kernel I think.
RPMS at
https://www6.software.ibm.com/dl/lxdk/lxdk-p
(you want the p-series for a mac)
James.