Very slow insert speed

Hi all,

I understand that the problem is by me, but do not have any idea how to
search it.

My configuration:

Dual Athlon MP 1800 MHz,
1 GB RAM,

Mandrake 8.2 with standart postgres install.

I try to insert 5000 records in a flat table with 10 column.
I am working with jdbc for my test.
The speed that I get is max. 20 rows per second inserted !!!

I think it is very low and I make the next step by inserting anoder 5000
rows. The time was 6 rows/sec.
Processor usage was 100% from the first processor and it is the maximum
.

By the next atempt I got one record per second.

How can I detect my problem and what is the normal speed for inserts?

Many thanks in advance.