There’s only one multiprocessing bottleneck left in DragonFly: vm_token.  Matthew Dillon’s working on removing it, and he’s been testing his initial results on a 4-core machine and a 48-core machine, using heavily parallelized buildworlds to test concurrency.  He’s posted the results, showing an initial speedup of up to 30%.  This definitely isn’t going to make it into 2.12, but it’s looking good already.  Keep in mind these are improvements on top of the performance graphed here yesterday.