Related: Network Optimization for SPAs and React Apps covers the modern optimization techniques that work with HTTP/2 rather than around HTTP/1.1's limitations. In 2012, a frontend developer optimizing a website's network performance would combine all their JavaScript into one file, combine all their CSS, put icons into a single sprite image, split their static assets across multiple subdomains, and inline small images as base64 strings in CSS. All of these were correct. They were the right things to do. By 2020, most of them were wrong. Not slightly suboptimal; actively counterproductive on HTTP/2. The underlying constraint they were designed around had been replaced by a better protocol, and the optimizations built for the old constraint became liabilities under the new one. What this covers: What HTTP/1.1's connection limit actually meant in practice, how Google's SPDY experiment led to HTTP/2, what multiplexing changes about the request model, and which of the old practices to stop doing today.…