The fastest demonstrated systems are those used by Southwest and railroads.

Southwest: No assigned seats. People self manage the boarding and seat assignment process as it happens. This was mentioned in passing in the Wired article. It still leads the alternatives by a large margin.

Amtrak Acela: No assigned seats, lots of doors, no need for seat belts, etc. This loads and unloads even faster. The equivalent of a full 727 loads in a few minutes at stations like NYC Penn. The limiting factor is clearing people through the ticket checking process, not getting them into seats.

TGV, Thalys: Assigned seats, lots of doors, no need for seat belts etc. This is slower than Amtrak, but does not delay the train schedule. They restrict access to the train platform so that they can check tickets in advance and send people to stand at the right place for the right door for their car on the train. Then two doors per car lets the train load as fast as Amtrak. You do spend more time standing around in the aisle on the train dealing with getting to the proper seat if the train is full. But the train can be moving.

The reality is that the major delay factor is the assigned seat. If you remove the assigned seat, the self managed seating is much faster than any of the assigned seat alternatives. As an extensive traveler I've found that I prefer faster through the system over assigned seating.