I thought I'd run a couple of tests to see if it would be helpful
against CVS from Aug 3, 2005.
Here's a run with autovacuum turned off:
http://www.testing.osdl.org/projects/dbt2dev/results/dev4-015/42/
5186.55 notpm
Autvacuum on with default settings:
http://www.testing.osdl.org/projects/dbt2dev/results/dev4-015/38/
5462.23 notpm
Would it help more to try a series of parameter changes?
Mark