Speed isn't important in the least, and guess what? Neither is kinetic energy. If you have a very low energy setup, you need to use a heavy arrow. Your's isn't so you can do okay with an average arrow configuration. If you're lucky enough or good enough to get an arrow that matches your setup you'll have an easier time getting your broadheads flying where you want. It really doesn't matter how your field tips are flying if your object is to kill a big game animal.

With beginners I think it is important to get tip weights of at least 125 grains and appropriately spined shafts. The better you can tune the arrow, the better you will shoot a broadhead, thus increasing your chances of killing what you're shooting at.