Walking Behind Slow People

So, being in college for two years, I've noticed this more than once and it's just a small thing that irritates me. I always walk to class instead of driving or taking the trolley just because I want the exercise. Well, everyday, there is always someone in front of me, walking, and I mean slow walking. If I had to give it some mathematical description, I would say for every 2 steps I take equals 1/2 of theirs. I mean, come on. I'm not saying to run to class or speed walk, but at least keep up with everyone else.