How do you increase FreeBSD processor performance by 10%?

Turn on powersaving! This may seem counter-intuitive. Old school admins typically turn off all power management in BIOS, and ensure their servers don't go into power saving modes for performance reasons. Today, this isn't necessarily true.

Why?

Intel Turbo Boost. This tech ramps up the single core clock speed in a multicore processor when it's able to (eg when other cores are idle) providing better performance. For this to work, it must be enabled in BIOS as well as OS. In Freebsd, that's handled by powerd (man powerd).

The best  practice now is to enable hiadaptive mode on powerd, which enables TurboBoost, with a secondary benefit of power saving. Some DCs are already billing customers based on power consumption (AIMS!), so this is good to have. That's like having your cake and eating it too.

 hiadaptive  Like adaptive mode, but tuned for systems where performance
   and interactivity are more important than power consumption.
   It increases frequency faster, reduces frequency less aggres-
   sively, and will maintain full frequency for longer.  May be
   abbreviated as hadp.

Edit your /etc/rc.conf,

powerd_enable="YES"
powerd_flags="-a hiadaptive"


Then

/etc/rc.d/powerd start

You're all set.