Running slow using the Parallel version?

I recall that the Distributed Parallel Reversi, xversi-java-parallel-v0.8b, was able to achieve reasonable speedup when the level of evaluation is large enough. However, when I run it on my AMD Dual-Core machine, I realize the serial version, xversi-java-v0.7a, is much faster. :S (Jaw drops). I then went to check changes between the serial and parallel versions, what would cause this to happen? ...... after much struggling, I find that I'm using gcj package. Phew~~~~~ The serial version running on GCJ is reasonably fast, but the evaluation is extremely slow in the parallel version. I suppose, the RMI implementation in GCJ is causing delays. Finally, I simply install latest Java package from SUN, and it just runs fast. :) So, now I can increase the level of evaluation to improve the computer's reversi skill.
From my timing of the runs of computer vs computer, it took merely 30 seconds to 1 minute for the SUN Java to complete. However, it took more than 10 minutes for the GCJ Java to run. I dont know how long it will take, I just give up running. :p