Blackdown JVM on Sparc Performance Poor

I was hoping to use this configuration but the performance of the
application is dismal.
 
For comparison I am using an Ultra 2/1 GB/2 x 300 running SuSE 7.3 vs an
Ultra 1/448 MB/1 x 200 running Solaris 7.
 
Blackdown JVM on Linux, Sun JVM on Solaris.
 
Using the same application and app config, instant response from the
Solaris machine vs 5 seconds from the Linux machine.
 
Any ideas?
 
Steve