Not sure what "higher" or "lower" pots means, but I've noticed a similar pattern in NSC, where pop votes would often come early and alternative late.
I remember I once found a study that linked music taste with personality, which said (among other traits) that people who liked pop scored high on "conscientiousness" meaning they tend to be more orderly and disciplined, and less flexible. That might make them more likely to handle tasks like voting instantly, while those on the opposite side prefer to procrastinate.