Here’s what those free apps with ad support really cost you: 79% more data use

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.