Modern websites make a lot of requests. And I mean a lot. And many of these requests are to third-party resources. As this trend continues, it is important to routinely analyze the performance cost of your site's resources to identify areas for optimization.One approach to such an analysis would be to aggregate requests at the domain-level. Using raw HAR data, the data that underlies the popular waterfall chart, we can calculate the performance cost of each domain that our site uses.