This was originally posted at the 2015 Performance Calendar. A lot of different factors can affect a web page's performance. For this reason, truly effective Web Performance Optimization starts with identifying the most significant perf bottlenecks of your site. This is usually done with tools like DevTools, WebPagetest, PageSpeed Insights,

Update: I presented a talk about this tool at the 2016 Reversim Summit. Slides can be found here. "Chunk Scatter" (github, demo) is a simple tool I wrote for analyzing HTTP responses that use chunked encoding. It plots each chunk on a scatter graph to help visualize when