JUnit.org Resources for Test Driven Development

I have a customer, within my Org, that uses junit. They approached me trying to resolve an issue they have. They moved from Solaris 5.9 to Sles 10 Linux platform.
99% of all process run much faster on the linux server. There is however one process that runs 40-60% faster on the Solaris server. Question: Is there maybe some tuning that needs to occur, I'm not 100% sure what the process is doing but am waiting for that response now.

Thanks,
DJ