I use the site through a mobile browser on my tablet. I tend to preload pages at home because I read on the train where there isn't much connection. Every time I interact with the screen, the site tells me I'm offline. This used to only happen on the final loaded chapter, but now it's happening on all of them. I'm guessing this change might be related to the high CPU usage.
It may be trying to keep track of your progress for your library better or there may be something inefficient with the infinite scroll. Of course ads are always suspect.
I'd love to know what it is so I'm not out of battery when I'm returning home. Otherwise, there's always reading material on less energy consuming sites.