I don't think it would be fair to compare these two locos as they were built for different types of traffic the "big boys" were built to haul
"VERY" heavy freight over steeply graded track & were capable of hauling 3,000 tons+
& thus were not built for speed.
http://www.youtube.com/watch?v=sOFD8FDaDI4
http://www.steamlocomotive.com/bigboy/
The Deltics were built to replace 55 east coast pacifics & were capable of 100mph+ but were not expected to haul more than 600 tons or so.