You may not spend a penny while you tap away in your favorite mobile game, but this doesn’t mean it doesn’t cost you in other ways.

Smartphone and tablet apps that feature advertisements are a drag on your device, according to a new study (via Science Daily). They drain your battery faster. The ad-heavy apps put an extra strain on the processor. And downloading the assets for the ads uses a ton more network data. So while software like this may not necessarily cost you cash, they do damage the experience of using that expensive handheld computer in your pocket. But with the mobile ad market making $17 billion last year, they probably aren’t going anywhere.

The study comes from University of Southern California researcher William Halfond, who collaborated with other researchers out of Rochester Institute of Technology and Queen’s University in Canada. Halfond will present the findings at the International Conference on Software Engineering in Italy this May.


VB has studied ads and other forms of monetization:
Mobile Games Monetization


The group found that apps with ads use, on average, 16 percent more power than ads that don’t feature commercials and popups. Some of the worst apps were actually 33 percent worse. A smartphone that would typically last 2.5 hours under harsh conditions only last around 2.1 hours on average with ad-supported apps. In the worst case scenario, certain power-hungry apps lower the battery life to just 1.7 hours.

Halfond’s study also reveals that ad-supported apps use 22 percent more memory and 56 percent more of the central processing unit. That’ll not only lead to more battery usage, but to an experience that feels more sluggish overall.

But ads are the worst when it comes to network usage. On average, apps with commercial videos and interstitial marketing used 79 percent more data. If you don’t have unlimited data, that could start to cost you money.

Using ads to generate revenue is a popular business model on mobile. The majority of people with smartphones don’t like paying for apps, and ads enable developers to earn some money from having thousands or even millions of people playing for free. It’s one of the ways that the free-to-play Flappy Bird made an estimated $50,000 every day despite featuring no way for players to spend money.

But Halfond’s study finds that people notice the difference. Apps that use them have a slightly lower rating of about .003 on average on iTunes and Google Play.

“In absolute terms, this is very low, but in the crowded and competitive world of apps, it’s a huge difference,” said Halfond. “It can make the difference between your app getting downloaded or going unnoticed.”