Large object insert performance.

I'm populating a new database from some text files. I'm using large objects
to store the body of the text files. I have a little thing setup to monitor
how fast the inserts are going. They started out at about 20/sec and have
been slowly dropping. I'm about 6% through my data and I'm already down to
2/sec and dropping. All I'm doing is inserting the large objects. No other
action is happening. Here's the portion of the script that is populating my
database:

self.db.query('begin')
body_lo = self.db.locreate(pg.INV_READ | pg.INV_WRITE)
body_lo.open(pg.INV_WRITE)
body_lo.write(puff.get('message/body', ''))
body_oid = body_lo.oid
body_lo.close()
self.db.query('end')

That is the full extent of my queries to the database. There are no tables
or indexes defined. The average size of a body is about 300 bytes, but it
goes as high as 30k.

Is there any way to speed this up? If the handling of large objects is this
bad, I think I might just store these guys on the file system.