DB Performance Tuning

Hello,

I am working on database performace tuning on Postgresql 8.1 database build on Suse 10 Linux dedicated server. I am having 32 GB of RAM and 8 CPUs.  

I have made minimum recommended settings under postgresql.conf (i.e shared_buffer, work_mem, and effective cache_size also kernel.shmmax)

I have run SQL queries using pg-admin, the query execution + retrieval time is 80% reduced over existing server.

But same I tested with JDBC, the query requires more time as compared with existing server.

Please help me out in this performance tuning.
Regards,
Nilesh