[Nick_C]

Is that still the case for FreeBSD? I thought they did some work this year to help speed it up. Also, the Linux emulation under FreeBSD was always slow for mutex (did you test under Linux emulation or native?), but they have implemented futexes now and pushed uncontended mutex to userspace to speed it up.

[LnxPrgr3]

I tested under native, but you raise an important point—IIRC I was testing with FreeBSD 7.1, and seeing as 9.0 is out it's definitely worth a retest.