That's a really good question. The communication between FlightMap and FlightConnect is really light weight and fast but it does happen many times a second. Over wifi you are not going to notice it at all as we're talking about bits. The google maps part of the application is where the majority of the data is going to come from. I believe that the app will utilize the google maps cache on the machine but the download of the tiles is the largest use of bandwidth. I honestly don't know how much that is. One thing to note is that I don't currently allow the connection between FlightMap and FlightConnect to be over anything other than wifi.