The social network rolled out changes that could determine which users see specific ads.

The importance of the role that mobile websites play in brands’ digital footprints is on the rise. And the experience consumers have on those sites is differentiating certain companies from their competitors.

But according to Matt Idema, Facebook’s VP of monetization product marketing, more than 40 percent of small businesses in the U.S. had not optimized their websites for mobile traffic as of February. In a recent Adweek article, he says, “Speed, a good user experience, meeting their expectations of something loading quickly. Going back to the research, that’s what people expect.”

That’s why Facebook is putting more pressure on brands to speed up their mobile websites—the goal is to get more mobile users to stay on a website after they click on an ad. This week, the social network started preloading ads before people click on them in an effort to decrease the overall loading time for mobile websites, which can ultimately prevent users from leaving sites before they finish loading.

That change has the potential to make a lasting impact—right now, Facebook says as many as 40 percent of its users leave a website if it takes longer than three seconds to load. However, there’s a catch for brands: Facebook is working on a way to incorporate load time into determining which users see specific ads.

To read the original Adweek article, click here.