Help tracking down problem with inserts slowing down...

I need some help tracking down a sudden, massive slowdown
in inserts in one of our databases.

PG: 7.2.3  (RedHat 8.0)

Background.  We currently run nearly identical systems
at two sites: Site A is a 'lab' site used for development,
Site B is a production site.

The databases in question have identical structure:

  A simple table with 4 columns with a trigger function
     on inserts (which checks to see if the entry already
     exists, and if so, changes the insert into an update...)
  A simple view with 4 columns into the above table.

All access is through jdbc (JDK 1.3.1, jdbc 7.1-1.3),
postgresql.conf's are identical.

The two sites were performing at comparable speeds until
a few days ago, when we deleted several million records
from each database and then did a vacuum full; analyze
on both.  Now inserts at Site B are several orders of
magnitude slower than at Site A.  The odd thing is that
Site B's DB now has only 60,000 records while Site A's is
up around 3 million.  Inserts at A average 63ms, inserts
at B are now up at 4.5 seconds!

EXPLAIN doesn't show any difference between the two.

Can someone suggest ways to track this down?  I don't know
much about postgresql internals/configuration.

Thanks!
Steve
-- 
Steve Wampler -- swampler@noao.edu
The gods that smiled on your birth are now laughing out loud.