Originally Posted by
tdracer
... as a result it tended to get less than optimum routing to keep it out of the way of the faster traffic.
This is mainly history now. Air traffic, at least in my part of the world, does not fly along airways - which were mandated by ground based navigation aids - any more. There is a growing number of countries that have abolished airways altogether. Aircraft now fly direct routes between convenitntly located waypoints. Therefore it does not matter what speed you fly at, because no other aircraft is flying the exact same route as you. There are exceptions like north Atlantic tracks, but I am certain that a solution to that problem will be found as well.