<head>Elm optimization instructions for using Terser, the --opimize flag, and elm-optimize-level-2
Dev tools performance tab
Ju Liu's article, Performant Elm, on analyze Elm performance using Chrome Dev Tools
Here's an in-depth conference talk on different script tag techniques. Ishows the differences between different ways to load script tags, including using async, defer, and in HTML <head> vs. <body>