4-5 main villians? It had a whole introduction arc in water 7 (38 anime chapters), robin`s background story in the middle of the arc , they fought a lot just to get into the bridge(18 anime chapters, excluding fillers) and THEN the fight with the main villians start (26 chapters). I thought the manga was pretty chaotic in these parts, especially the getting to the bridge part.
Maybe i`m wrong thogh, it`s all a matter of perception. To ME One piece is often chaotic and always feels slow as hell.