At the end of Chapter 2, just after discovering the pearl, while still in his canoe, Kino yelled as he was overcome with emotion. Men in other canoes paddled over to see what the commotion was about.
In Chapter 3, the narrator describes a town as one living, breathing animal with a nervous system. In other words, the town is one entity; all individuals are connected. But the news travels even faster because the pearl represents the potential for prosperity. The pearl represents hope for Kino and Juana, but they soon discover that it represents profit for others.
"News seems to move faster than small boys can scramble and dart to tell it, faster than women can call it over the fences" (10). The news travels fast because it is a small town but also because although some people in the town see this as a blessing for Kino and Juana, more begin to think how this might benefit themselves. The pearl buyers, beggars, the doctor who refused to treat Coyotito, and even the priest all flock to Kino to see how they might profit from his good fortune.
News travels fast in a small town. But it is really the greediness of the townspeople that speeds up the facilitation of the news.