So how quickly does the stock market react to new information?

According to this news note in this case "almost instantly."

Close to midday on Thursday, Google’s financial printing partner, RR Donnelly, published the search giant’s earnings release draft hours before it was supposed to. The result: Shares of Google dropped sharply and almost instantly by nearly 75 points, with the unexpected gaffe only compounding the fact that Google missed its quarterly expectations. . . .