Which performance can I expect? I'm running a Postgres 9.1 database on a Debian Squeeze server. It's a paravirtualized XEN guest system with 4G RAM and 1 CPU core, based on a i7-2600 host system with Linux software-RAID1.

I'm trying to get a feel for how fast/slow my setup is, and am running pgbench. This is the command I've been running to initialize pgbench:

pgbench -i -s 100 -U jboss -p 5432 -h 127.0.0.1 project2_core


The first 5000000 tuples run by very quickly, but then it gets slower and slower. Now, it displayed

10000000 tuples done.


for a very long time (10 minutes or so) with no CPU load, and also RAM is not an issue. Only then, it continued with 

set primary key...


and some NOTICEs about primary keys.

My question: is this runtime to be expected, or must I suspect there's something wrong with my system?
I'd look at how you have your IO stack set up, which you say nothing about in the question. It sounds like actually committing the rows is taking a really long time.  Virtual file systems on top of other file systems often display the worst characteristics of both layers.

You also should try doing an actual test run, as well as just populating a database.