Sepherosa Ziehau has been doing a lot of work with various processors states to save power on DragonFly.  He’s published a summary of how well the various P-state/C-state/mwait settings work.  He found that setting a lower C-state can perversely improve performance.

For those saying “but how do I set these lower power states?”:

sysctl machdep.mwait.CX.idle: AUTODEEP

sysctl machdep.cpu_idle_hlt: 1 (or higher)