benchmarks with pgbench

Hi Guys,
I''ve been running pgbench tests for a while. I have one server set up
to run pgbench tpc tests (7.x). A new server that I just configured
with SUSE and 8.0.0 just gets killed even though it has the same memory
8 GB and it's a x86-64 box. The other one is Solaris full 64-bit. That
seems reasonable, but we thought postgres would run better on a linux
box than solaris. Also, the x86-64 box does much worse than a 32-bit
linux box with mandrake and a lot less RAM. I've restarted postgres
with many different postgresql.conf configs and nothing seems to make
much of a difference to pgbench. Has anyone else experienced slower
performance on 64-bit linux as compared to 32-bit linux?

D.J.