Does More Bandwidth Really Not Matter (Much)?

The prevailing wisdom is that more network bandwidth does not matter much and that website performance is primarily limited by network latency. However, as mobile websites become more complex and mobile network performance improves, does this adage continue to hold? To understand the effects of small changes in network bandwidth and latency on website performance, we propose a novel webpage characterization metrics, Critical Path of Improvement (CPI). We compute CPI for 45 websites and analyze it against the network performance of four mobile ISPs in 57 US cities. Our results show that 18% of websites are primarily limited by bandwidth with others limited by bandwidth to some extent. These results show that contrary to accepted wisdom, insufficient bandwidth is a limiting factor in some website/network combinations. We also offer a discussion of approaches website developers and mobile network administrators can follow to understand and mitigate bandwidth limitations to website performance.