How about your position? Is it identical? I went from a 15 year old AL bike to a 2013 Madone. I thought for sure I was suddenly faster. My first few rides were actually faster because of my extra excitement on the new bike. Over time, I realized the bike really added nothing to my speed. If I wheel out the old bike and hit the same road today, it'd be nearly identical. That said, the new bike has a smoother ride, so I can ride harder for longer. In that sense, it is a faster bike perhaps, but that is probably 90% switching from 23mm gatorksins to 25mm gp4000s.

Edit: let's not forget that all of this can be quantified with a power meter. Same position, same wind, same watts, yet more speed? Faster bike.