Bound parameters on Linux are extremely slow (compared to unbound and/or Windows)

Hi, everyone. A project I'm assisting is connecting to PostgreSQL (9.2)
via JDBC. We're experiencing extremely slow query execution, for
precisely the same queries, depending on (a) operating system and (b)
whether we use bind parameters.

We're using two different Red Hat Linux systems (one running RHEL 5, and
the other RHEL 6). The machines have 16 GB and 64 GB RAM, respectively,
with 4+ GB allocated to shared buffers on each one. However, given that
the performance difference is between psql and JDBC, I doubt that these
are significant factors.

We have two different Java programs (which do 1,000 inserts), each of
which we've run 10 times on each of Windows and Linux. The average
time needed for running each program is:

Windows: 232 ms with binding, 152 ms without binding
Linux: 2,233 ms (yes, 2.233 *seconds*) with binding, 176 ms without binding

We've also run the same 1,000 inserts via psql on a remote machine, and
the timing was quite fast (i.e., like what we saw on the Windows machine).

The combination of binding + Linux seems to be the problematic one here,
but I'm at a loss for why.

I can provide the test programs if they'll help, but I'm first wondering
where the problem might lie.

Any suggestions or ideas? What additional information (e.g., the test
programs) would help to track this problem down?

Thanks in advance,

Reuven

--
Reuven M. Lerner -- Web development, consulting, and training
Mobile: +972-54-496-8405 * US phone: 847-230-9795
http://lerner.co.il * Skype/AIM: reuvenlerner