NetBSD, OpenBSD, *BSD and FreeBSD compared
Solution 1:
Are you looking for something like this?
Solution 2:
See this posting on serverfault for some links to web resources on BSD. It also has links to documentation and benchmarks on the SMP improvements in the FreeBSD 7.x kernel. The devs claim it is better than a fairly recent 2.6 kernel and show benchmarks on an 8 core box.
Solution 3:
Wikipedia has an entire article devoted to the comparison of the *BSDs.
Here is a good kernel trap article comparing NetBSD to FreeBSD.
And here's another straight from the FreeBSD website.