As if you needed another reason to hate those annoying in-app ads, a recent study shows that they play a large part in the drain on your battery.
With Angry Birds, for example, the gameplay was only responsible for about 30% of the total battery drain. The remaining 70% was attributed to location tracking, user information data, and the download and display of ads. Swell.
Not all apps had quite the same results, but enough to still tick you off. Granted, the testing was conducted by Purdue University and *ahem* Microsoft, but the information still data still looks correct.