Among popular apps like Angry Birds, Facebook, Free Chess and NYTimes, as little as 10 to 30 percent of the power consumption went toward powering the app's core functionality:
Abhinav Pathak, a computer scientist at Purdue University, Indiana, and the author of the study's report (PDF file), said that app developers need to take energy optimization more seriously, reports the BBC. Pathak and his fellow researchers built a special tool called eprof to monitor the energy use of Android and Windows Mobile* apps. They tested popular apps like Angry Birds, Facebook, Free Chess and NYTimes as case studies and found that only 10 to 30 percent of the energy spent went toward powering the app's core functionality. In Angry Birds, only 20 percent of the total energy cost was used to render and run the game. Forty-five percent of the energy was spent tracking the user's location with the GPS and uploading that information, then downloading location-specific ads over a 3G connection. The app kept the 3G connection open for around 10 seconds, even if the data transmission completed in less than that amount of time. This "tail energy" cost another 28 percent of the app's energy usage.Source: Neowin