How much bandwidth does a Facebook app use like say farmville?

The bandwidth usage of a Facebook app like FarmVille can vary significantly based on factors such as the number of active users, the complexity of the game, and the frequency of updates. Generally, social games do not use excessive bandwidth per session, often ranging from a few kilobytes to several megabytes, depending on the graphics and real-time interactions. Overall, while individual use may be modest, the cumulative bandwidth can be substantial when considering millions of users.