Train for It
Can't skip this one. No amount of these other prep steps will take one very far without a solid amount of training logged. "You just have to train," Ueli Steck told me at the Outdoor Retailer Show when I chanced to meet him for a few moments. Couldn't agree more.
Candy bars and junk food taste great, but there are few high performing athletes who don't attempt to get a decent medley of healthy foods into their bodies before a speed attempt. During a speed attempt, fluid based energy gels such as GU Roctane are far superior to solid foods—they don't divert nearly as much precious blood away from one's muscles (to the stomach) to aid in digestion.
On extended outings, this makes a huge difference. Avoiding time-sucking maneuvers such as getting lost or getting off trail is vital to maximizing speed. Knowing where you can turn on the gas, or where you need to simply coast, is also important.
A lot of people scoff at the notion of trimming every extra ounce on a speedy outing. Strangely, these seem to be people who aren't making speed attempts of their own. Ounces count, but more importantly, pounds make a huge difference during extended mountain travel. Considering an extra PB&J sandwich? If it's not required, get it out of there. Better to be somewhat hungry (read: ravenous) when you return to the trailhead than to lug a surplus sandwich around during your effort. Do you really need a softshell or will your efforts keep you warm even in a rainstorm? Or will you be fast enough to beat that rainstorm? Every item is worth considering.