I did some comparative benchmarking between the 2.6, 2.8, and upcoming 2.10 release for DragonFly.   As several people have guessed, performance has improved significantly, and the difference would probably be even more pronounced if I was using more modern hardware,  e.g. swapcache or a system with AHCI.  I have a mailing list post with details, and here’s the graph that sums it up:

(Sorry, no Lazy Reading this week.  Life didn’t co-operate.  At least there’s a pretty graph!)