That third night he found his way more quickly than before. He was walking so fast he knew he was making more noise than was wise, but he didn't meet anyone.
I don't understand the structure of "making more noise than was wise". I guess it means if he managed in a wise way, he wouldn't be making so much noise. But I'm not sure if my understanding is correct. Can someone help to explain its structure and meaning?
-- Excerpted from Harry Potter.