That chart is 18 months old. FreeBSD 10 got a number of SMP-related improvements (and some for ZFS as well, if I'm not mistaken). It'd be interesting to see an up-to-date comparison with FreeBSD 10 (and maybe 11-CURRENT), DragonFlyBSD 3.6, and NetBSD 6.1 (and maybe a couple of Linux distros for good measure).
http://www.dragonflybsd.org/performance/