Francois Tigeot benchmarked several different operating systems using Postgres 9.2b3, including DragonFly, and published the results. I have a local copy of the PDF since the attachment didn’t really survive the archiving. Follow the thread for discussion. The Linux results look abnormally high, so it is possible that something different is happening on that platform…
A running description of activity related to DragonFly BSD.
You can also get the file via other mail list archives, linked at http://www.dragonflybsd.org/mailinglists/
Anyway, newer version, with more tests, is linked in followup:
http://leaf.dragonflybsd.org/mailarchive/kernel/2012-08/msg00035.html
…or you just `base64 -d` what is shown on http://leaf.dragonflybsd.org/mailarchive/kernel/2012-08/msg00022.html ^^