The results of the ARC does not say much about the performace of the boats, most crews are cruisers, not racers, family crews that will enjoy the journey, not to compete, with heavily loaded boats.
Sailing between Thailand and Europe with a crew of Chilean racers we never use the autopilot
and there was always someone who was tuning the sails, so we kept close to the maximum speed that the boat could give. We went two or three days after a flotilla of cruisers with which we share in Thailand, Sri Lanka and Maldives and arrived a day ahead of them. We kept the spinnaker
all the time, even did spinnaker
changes as the wind, while the cruisers reduced sails at night.