The Webkit blog, on how to optimize your pages so that they don’t drain the battery of your visitors their devices:
Users spend a large proportion of their online time on mobile devices, and a significant fraction of the rest is users on untethered laptop computers. For both, battery life is critical. In this post, we’ll talk about factors that affect battery life, and how you, as a web developer, can make your pages more power efficient so that users can spend more time engaged with your content.
The three sections where to optimize covered are scripting, painting (the way stuff is rendered/animated), and networking (requests over the network)