Lighthouse gives you a score. What it rarely gives you is the one sentence that tells you what to change in code tomorrow morning. Each of these ten tools turns a vague Lighthouse finding into a specific fix.
1. Early Hints (103) Audit
HTTP 103 lets the server send Link: preload / preconnect hints before the final response. Cloudflare, Fastly, Vercel, Akamai all support emitting them. Chrome and Edge honor them. Typical LCP improvement: 100-300ms. The tool detects whether your origin actually does this, and which hints it sends.
2. CrUX Field Data Probe
Google ranks on real-user p75 from the Chrome UX Report, not your Lighthouse run. This probe calls the PageSpeed Insights API, pulls the 28-day CrUX data, and shows LCP / INP / CLS / FCP / TTFB rated against Google thresholds. Mobile or desktop strategy toggle.
3. Compression Codec Audit
Lighthouse tells you "compress your responses." It doesn't tell you which codec. Brotli beats gzip 15-25% on HTML/CSS/JS. zstd is even better but less broadly supported. This audit checks your Content-Encoding, probes subresources for brotli coverage, verifies Vary: Accept-Encoding is present (otherwise your CDN caches the wrong codec), and reads Alt-Svc for HTTP/3 advertisement.
4. Critical CSS Inlining Audit
Counts render-blocking stylesheets, measures inlined <style> bytes, detects media=print onload defer patterns, and flags missing font preload hints. The fix prompt walks you through critters / critical / penthouse for automated extraction.
5. Font Loading Strategy Audit
font-display is the difference between FOIT (invisible text for 3 seconds) and FOUT (visible fallback, smooth swap). The audit checks @font-face declarations, preload hints, woff2 coverage, Google Fonts display=swap parameter, crossorigin on font preloads, and variable font usage. Each is a one-line fix.
6. Preconnect + DNS-Prefetch Hygiene
Lighthouse flags "unused preconnect" with no guidance on which ones to keep. This audit enumerates every third-party origin the page actually loads, compares against your preconnect list, flags unused preconnects, identifies heavy origins missing a preconnect (fonts.gstatic, googletagmanager, image CDNs), and verifies crossorigin attributes on font preloads.
7. Speculation Rules API Audit
Chrome 121+ native prerendering makes multi-page sites feel like SPAs. The audit parses <script type="speculationrules"> blocks, validates prerender + prefetch rules, checks eagerness levels (moderate vs immediate), and flags missing prefers-reduced-motion guards.
8. Image LCP Candidate Audit
Finds the probable LCP image, flags loading="lazy" on the hero (the #1 silent LCP killer), checks for fetchpriority="high", missing width/height, absent srcset, and legacy formats (JPG/PNG instead of WebP/AVIF).
9. Response Size Budget Audit
Measures HTML, CSS, and JS transfer bytes and checks against common budgets (200 KB HTML, 500 KB CSS, 500 KB JS, 2 MB total). Flags approach to Google's 15 MB HTML crawl ceiling.
10. View Transitions API Audit
Chrome 126+ cross-document animations. The audit checks for @view-transition CSS, document.startViewTransition(), view-transition-name usage, ::view-transition-* pseudo-elements, prefers-reduced-motion guards, and pairing with Speculation Rules prerender for instant animated nav.
Bonus: Responsive Image Audit and Non-Composited Animation Audit
Two batch-10 additions from the fixes2.txt round. Covered in the Lighthouse fixes post.
How they integrate
Every tool above is wired into the Mega SEO Analyzer v2 as a specialist deep-link. Run the orchestrator on your URL; when Performance dimension fails, the specialist is one click away with the URL pre-filled.
Related reading
- Mega SEO Analyzer v2 — the orchestrator
- Lighthouse ran fixes2.txt — real audit, 5 new tools
- CWV field vs lab gap — why Lighthouse disagrees with CrUX
Fact-check notes and sources
- RFC 8297 HTTP 103 Early Hints: IETF spec.
- Chrome Speculation Rules API: web.dev.
- View Transitions API: Chrome 126 release notes.
- Core Web Vitals thresholds: web.dev/vitals.
- Brotli vs gzip compression ratios: Google Brotli GitHub.
This post is informational, not performance-engineering or consulting advice. Mentions of Google, Chrome, Cloudflare, Fastly, Vercel, Akamai, PageSpeed Insights, and similar products are nominative fair use. No affiliation is implied.
