Since the conclusion of the SMPng project, the focus of SMP development in FreeBSD has shifted from deploying locking infrastructure to careful profiling and optimization of kernel SMP strategies for increased performance on common workloads. FreeBSD 7.0 was the first release to benefit from this optimization work.


The status of this work includes MySQL workload benchmarks and memory allocator performance in the new FreeBSD 8 branch. Also, here is a recent presentation showing FreeBSD compared to several other operating systems like NetBSD, DrangonFly, Solaris, and Linux.

Source: osnews.com (11/03/2008) where you can also read a lively FBSD vs Linux comments thread.