Publishers are reportedly concerned about the lack of revenue they make through Google’s Accelerated Mobile Pages (AMP) because ads load slower than content via the initiative.

According to Digiday, citing six publishing sources, there is a discrepancy considerable discrepancy between content and ad loads times, which means people tend to scroll past ads before they’ve loaded and, as a result, are unviewable. This has resulted in one publisher’s revenue per page on AMP being less than half of what it gets on its own properties.

Despite the discrepancy, it is not clear how much of this is actually down to the speed in which AMP loads content, because AMP, purposefully, also restrict page design, recirculation, and the types of ad units that publishers can use.

Google has worked on trying to bridge the gap between the loading speeds of content and ads. However, for all its work, not much has changed. But this isn’t entirely Google’s fault, as ads tend to be a lot heavier than content.

Despite this, Google is honest about the role of AMP and how it is always going to put loading times and user experience first.

“The aim of AMP is to load content first and ads second,” a Google spokesperson told Digiday. “But we are working on making ads faster. It takes quite a bit of the ecosystem to get on board with the notion that speed is important for ads, just as it is for content.”