One of the exciting things that the US Higher Education system offers is a diverse and incredible variety of courses for undergraduates. While some of these courses may seem irrelevant to your passion, they may in fact make you better in your chosen field because they allow you to see things from a different perspective than you normally would. I encourage you to try some of those classes that are in a different sphere so that you broaden your outlook on topics as well as humanity. You may be surprised to find a new passion! There is no wasted time if you learn something new.
The other advice I would give is to treat college as a full time job. Plan on "working" (either attending class, studying or researching) for at least 40 hours per week. This still allows for recreation time which is much needed to keep your mind fresh for the tasks needed to be a good student. Remember that part of the college experience is designed to allow you to connect with your peers and find outside interests. These are life skills which are also needed after you graduate. So, while they could be perceived as "Wasting Time", they do have an inherent value to develop other skills and increase your understanding of those around you.