Really bad insert performance: what did I do wrong?

I've use PostgreSQL for some pretty amazing things, and was a proponent
of using it here. I set up 7.3.1 on my development RedHat 8 box, and it
was fine. I need to load about 700,000 rows into one table, the rows
only having 6 columns, and the load on my box happens in just a couple
of minutes (there's some calculation while the data is loading, and that
time was acceptable to me).

My box, however, isn't a production server, so I attempted to create the
database again on a Sun Blade:

SunOS trident 5.8 Generic_108528-17 sun4u sparc SUNW,UltraAX-i2
Status of processor 0 as of: 02/21/03 10:10:10
Processor has been on-line since 01/13/03 13:53:51.
The sparcv9 processor operates at 500 MHz,
and has a sparcv9 floating point processor.

It isn't the world's fastest box, but should be fast enough for this.

However...

It took almost 2 days to load the table on this box. The postgresql
process was constantly eating up all of the CPU time it could get, while
loading, at times, less than 1 row a second.

Now, I KNOW something is wrong, and it probably isn't postgres. :)

I turned off the index on the table (there was only one, on three
fields) and made the whole load happen in a transaction. The 2 day
result was after those changes were made.

I compiled postgres myself, using the gcc 3.2.2 package from sunfreeware.

Any thoughts? I know that postgres should be more than capable of
loading this data quickly on this box...I figured it could possibly take
twice as long...and I thought my problem would be i/o related, not CPU.

Thanks!

Kevin