The Dhrystone 2 performance as measured by the BYTE Unix Benchmark was in favor of PC-BSD 7.1 by a slim lead.
When looking at the integer arithmetic performance, the lead returned to Kubuntu.
At floating-point arithmetic performance too, the Tux-bearing operating system was in front.
Ending out our PC-BSD 7.1 vs. Kubuntu 9.04 testing was complex connect-4 solving using Fhourstones. In this test, Kubuntu delivered slightly more Kpos per second over PC-BSD 7.1.
As a whole, Kubuntu 9.04 performed much better than PC-BSD 7.1 in these tests. Some of these performance differences may be attributed to PC-BSD 7.1 / FreeBSD 7.1 using the slightly older GCC 4.2.2 release compared to GCC 4.3.3 in the Jaunty Jackalope release for Ubuntu and Kubuntu. In a few benchmarks, PC-BSD had the upperhand over Kubuntu. PC-BSD was better with Dhrystone 2 and complex ray-tracing using POV-Ray.
You can replicate these tests for yourself or on other Linux and BSD operating systems using the Phoronix Test Suite.