Found a research paper measuring differences in performance and efficiencies between Himalayan porters and caucasians and embedded and wrote something up.

Porters are not only better acclimated and lighter, they also move more efficiently, seemingly due to a more horizontal trunk posture which they are able to control well.

Of all y'all that have observed porters, do you notice a different walking style? outside of the whole barefoot thing

I can't imagine the porters on Kilimanjaro are more efficient. They seem to do just about everything they can to make it appear to be a struggle, from the way they walk, carry, etc...

Though I suspect once the client and their money gets out of view the efficiency increases dramatically.