Performance - fsync-off

Hi,

I just got my Postgres-database up and running, putting in data using a
Python-script, using the latest version of the PyGres-module by
Darcy@druid.net. It works great! But insertion seems slow, even though I
just got a few indexes. How can I turn off the fsync-variable? There must be
a way to turn it off when starting the database, like postmaster -x where x
is some command-line option or a setting in a config-file etc. I haven`t
found anything in my search so far. What will this do in terms of
performance ( 1-5 times ??? ) and is it considered safe? ( I`m running Linux
)

How does PostgreSQL compare in terms of speed compared to other databases,
commercial products included??

Thomas