adobecom/perf-tools
Page-load performance skills: perf-preload generates static LCP preload links from traces; perf-ab runs before/after comparisons of production URLs (Milo / MAS PRs, head.html snippets, guarded patches) with real Lighthouse 13.6.0 mobile with DevTools throttling (Slow 4G, 4x CPU), on a verified-US GitHub Actions runner by default or locally with --local, and analyzes DevTools traces
Run before/after page-load performance comparisons with the perf-ab CLI (adobecom/perf-tools). Always runs real Lighthouse 13.6.0 with the mobile profile and real DevTools throttling (Moto G Power, Slow 4G, 4x CPU), by default on a GitHub Actions runner with verified US egress, or on this machine with --local when the user says to run it locally; cold (new Chrome + empty profile per run, no warm-ups), alternating runs; downloads the official Lighthouse reports, traces and before/after medians. Compares a production page (e.g. www.adobe.com) as-is against an injected head.html snippet (e.g. preload links), fetchpriority changes, guarded source patches, Milo / MAS PR files or branch values. Also analyzes DevTools trace JSON files attached by the user. Use when asked to "compare before and after", "A/B test", "perf test a milo/mas PR or branch", "measure the impact on LCP/TBT/PageSpeed score", "test preloads", "run traces", or when the user attaches Trace-*.json files to compare.
Generate static preload <link> tags for a page's LCP with the perf-preload CLI (adobecom/perf-tools). Records a production page several times through perf-ab (always real Lighthouse 13.6.0, mobile profile with real DevTools throttling; by default on a verified-US GitHub Actions runner, or locally with --local; every load cold with a fresh Chrome and empty profile, no warm-ups), finds the LCP element in each trace and the scripts, stylesheets, fonts, GET JSON/HTML data fetches and LCP image that finished loading before it, and writes a head.html snippet of <link rel="modulepreload|preload"> tags. Then validates the snippet with perf-ab. Also analyzes DevTools trace JSON files attached by the user. Use when asked to "generate preloads", "what should be preloaded for LCP", "find the LCP critical resources", "build a preload list / head.html snippet", or "why is LCP late on this page".