Jason Grigsby of Cloud Four utilizes data from Akamai IO to theorize reasons for the large difference in browser usage between iOS and Android phones. What Grigsby finds amongst this data becomes quite interesting once he splits browser usage between WiFi and Cellular Networks.
I think this data shows the importance of load time awareness. Folks that rely on their phone's cellular data plan are more sensitive to load time. Longer time means more data. More data means more money and the faster the end user will cancel downloading a large site.
On a related note, be sure to check out Dave Olsen's Throttle, which simulates load time on slow network connections.