well returning from holland in 04 and America in 06, i have yet to get though manchester quicker than Atlanta! though Off topic, Michael palin went into China on his around the world in 80 days trip in less than 1 hour.
As far as I am concerned the biggest pain about flying to the USA is having to be at the airport 3 hours before take time 
. The time taken to go through immigration on landing is USA is insignificant compared to this. Will the new system change things???
thats normal, they have to scan and load stuff onto the plane so they can calculate things like how many meals they need and how much avgas they need in the jet to get the best gas milage.
I had a 3 hour wait when going from UK to the netherlands and that was a 45 seat puddle jumper and not a 200 odd seat 767. whether you are going from london to glasgow, london to Atlanta, or london to sydney, the 3hr check in is normal, that will never change
