The smart light bulb will react more slowly than a traditional wired light bulb. Using an app and a WiFi connection to control the bulb introduces a tiny bit of lag versus flipping a switch wired directly to the bulb. These delays can run anywhere from one to five seconds, depending on your system. And while you still may be able to control the basic on/off function with a manual switch, any other features of your smart bulb won’t be available if your WiFi service goes down.