As is well known, the Hobbit was written from the stories that Tolkien told to his kids. The pacing of the story reflects that. While each chapter contributes in some way to the overall narrative of getting to (or in, or out) of the lonely mountain, the book is constantly filled with little climaxes for each chapter as each substory (or night's reading) comes to an end. Think the encounter with the trolls, or when they're capture by goblins etc.