I think you are not alone. Last week i was looking at the new made ,but old style steel ,English Pashley bike site. A 40ish guy did a 5 mile time trial with his very light carbon 27 speed bike and a twice as heavy 3 or 5 speed internal hub Pashley Guv'nor. The carbon bike won by only 24 seconds and .7 mph. 22.6 to 21.9 mph. Page 4 or 5 in the owner photo testimonials. I seem to have similar cruise speeds on all the bikes i have used. But i never had an expensive bike. Your fast bike seems to have a smaller post angle? And taller also.