Perception is definitely a tricky thing; especially when it comes to the perception of speed and how well an experience performs.
There could be two sequences that happen in the exact same amount of time, but how they are executed can change a users perception of how well they perform. Taking a look at loading this is no different. In internet filled with spinning beach balls and hourglasses of falling sand grains how one executes a loading sequence can be quite effective in making an experience feel that much more responsive.
We found a white paper by chris harrisonfrom 2007. A few years old it still holds true and has an interesting study of responses to how visuals are updated on a screen and users perception of those updates.
Worth taking a look.