Phoenix LiveView vs Rails Hotwire: I Built the Same Real-Time App in Both. The Numbers Aren't Close TL;DR — Phoenix LiveView delivers ~5× more HTTP throughput and establishes WebSocket connections ~14× faster under load. Rails is not broken — it's a mature, productive framework — but for real-time collaborative applications, the Erlang VM is a different league. Why I Did This Every time the Phoenix vs Rails debate comes up online, the arguments are the same: "Phoenix is fast but Elixir has a small ecosystem." "Rails is slow but you can hire Rails developers." Nobody shows numbers from a fair, controlled experiment. So I built the exact same app twice — a collaborative real-time todo board — once in Phoenix LiveView and once in Rails 8 + Hotwire. Same features. Same HTML structure. Same Tailwind classes. Different everything underneath. Then I hammered both with k6 and a Node.js WebSocket flood and let the data speak. The source code and CI results are open on GitHub .…