Interactive tool to compare airlines' speed from A to B
 

Nate Silver and his people have built a nifty interactive tool at http://fivethirtyeight.com/interactives/flights/

Select your city pair and it compares the airlines' historical travel time, measured from the scheduled departure time. You can see who's been naughty and nice.

The methodology is described at http://fivethirtyeight.com/features/...astest-flights

My inference is that airlines with better performance have built more slack into their turns, so that planes spend more time sitting at gates. That cost needs to be balanced against the need to keep fares down.