I got to see AF1 Take of from Elmendorf AFB back in 2002. I was a ways away driving, it shot into the air much faster than the other 747s that take off out of ANC
. I am sure it has lots to do with the load factors on the respective planes. A heavilty loaded cargo vs one with 100 or so people in it. I may not be a GWB fan, but I do love seein AF1 when the chance arises.