High cpu usage after many inserts

Hi list,

We are running postgresql 8.3.5 and are trying to stress test our LMS.
The problem is when our stress tester (Jmeter) inserts around 10,000 rows
(in 3 hours) over 2 tables (5000 rows each table) the CPU of the sql server
hits 100% over all 4 cores for all future inserts.

I have tried numerous things to get the cpu back down but so far the only
thing that works is deleting the 10,000 rows Jmeter inserted.

For more information on the problem along with a time stamped list of test
results and outcomes please see
http://spreadsheets.google.com/pub?key=pu_k0R6vNvOVP26TRZdtdYw

Any help would be appreciated

Regards,

Jordan Tomkinson
System Administrator
Moodle HQ