Audit Speed
Run a structured Core Web Vitals and page-speed audit with root-cause trees before you ship or iterate on a slow marketing site or SaaS frontend.
Overview
Audit Speed is an agent skill most often used in Ship (also Launch, Operate) that deep-audits Core Web Vitals and page speed with threshold tables, LCP root-cause trees, and optimization guidance.
Install
npx skills add https://github.com/calm-north/seojuice-skills --skill audit-speedWhat is this skill?
- Official Core Web Vitals thresholds table for LCP, CLS, INP, FCP, and TTFB (Good / Needs improvement / Poor).
- LCP root-cause decision tree tied to largest-contentful-element failures and fix patterns.
- Pre-audit context gather: target URLs, existing Lighthouse or PageSpeed data, tech stack, and non-removable third partie
- Deep speed focus with resource-size and optimization recommendations; points to diagnose-seo for broader technical SEO.
- Suggests Google PageSpeed Insights when the user has no baseline measurements.
- 5 Core Web Vitals-related metrics with Good/Needs improvement/Poor thresholds (LCP, CLS, INP, FCP, TTFB)
- LCP root-cause tree for largest-contentful-element diagnosis
Adoption & trust: 2.2k installs on skills.sh; 10 GitHub stars; 3/3 security scanners passed (skills.sh audits).
What problem does it solve?
You know a page is slow or failing CWV but lack a structured way to tie LCP, CLS, and INP scores to concrete fixes on your stack.
Who is it for?
Solo builders shipping marketing sites, landing pages, or lightweight SaaS frontends who have (or can run) PageSpeed/Lighthouse data and want agent-guided diagnosis.
Skip if: Teams needing only a one-click CI Lighthouse gate with no editorial triage, or issues that are purely indexation, crawl, or on-page SEO without a performance angle—use diagnose-seo instead.
When should I use this skill?
User asks about page speed, Core Web Vitals, LCP, CLS, INP, FCP, TTFB, Lighthouse scores, why a page is slow, performance optimization, or resource size analysis.
What do I get? / Deliverables
You leave with prioritized speed fixes aligned to CWV bands, scoped to your URLs, stack, and third-party constraints—not a generic performance lecture.
- CWV threshold assessment per metric
- LCP-oriented root-cause hypothesis list
- Prioritized optimization recommendations respecting stated constraints
Recommended Skills
Journey fit
Spans multiple journey phases - primary shelf plus alternate fits below.
Performance and Core Web Vitals are a primary ship gate for solo builders who need pages fast enough to convert and rank. Canonical shelf is ship/perf because the skill centers on LCP, CLS, INP, FCP, TTFB thresholds, Lighthouse-style diagnosis, and resource optimization—not broad technical SEO (use diagnose-seo for that).
Where it fits
Homepage LCP is poor after a hero image change—walk the LCP root-cause tree and prioritize fixes before release.
Pre-launch checklist: confirm CWV are in the Good band on key landing URLs cited in search and ads.
New blog templates spike CLS—instrument layout stability before publishing a content burst.
Regressions after adding analytics scripts—compare INP and third-party impact with documented constraints.
How it compares
Use for CWV and speed root-cause depth; use diagnose-seo when the problem is broader technical SEO, not vitals-first performance.
Common Questions / FAQ
Who is audit-speed for?
Solo and indie builders using AI coding agents who own frontend or marketing site performance and need structured Core Web Vitals audits without hiring a performance consultant for every change.
When should I use audit-speed?
Use it during ship perf checks before release, at launch when SEO depends on fast LCP on money pages, after deploy when CWV regress, or whenever someone asks about Lighthouse scores, INP, CLS, or why a specific URL is slow.
Is audit-speed safe to install?
Review the Security Audits panel on this Prism page for install risk and upstream repo signals; the skill is guidance-only and does not by itself execute scans—you choose what tools and URLs to run.
SKILL.md
READMESKILL.md - Audit Speed
# Audit Speed Deep Core Web Vitals audit with root-cause analysis trees and resource optimization recommendations. ## Core Web Vitals Thresholds | Metric | Good | Needs Improvement | Poor | |--------|------|-------------------|------| | LCP (Largest Contentful Paint) | < 2.5s | 2.5s - 4.0s | > 4.0s | | CLS (Cumulative Layout Shift) | < 0.1 | 0.1 - 0.25 | > 0.25 | | INP (Interaction to Next Paint) | < 200ms | 200ms - 500ms | > 500ms | | FCP (First Contentful Paint) | < 1.8s | 1.8s - 3.0s | > 3.0s | | TTFB (Time to First Byte) | < 800ms | 800ms - 1800ms | > 1800ms | ## Before You Start Gather this context: 1. **Which pages?** Homepage, key landing pages, or specific slow pages. 2. **Current scores.** If the user has Lighthouse or PageSpeed Insights data, start there. 3. **Tech stack.** CMS, framework, hosting — this determines which optimizations are available. 4. **Known constraints.** Third-party scripts they can't remove, design requirements that limit optimization. If no data is available, suggest running Google PageSpeed Insights on the key URLs. ## LCP Root-Cause Tree LCP measures when the largest visible element finishes rendering. Diagnose: **Is TTFB slow (> 800ms)?** - → Server response time issue - Check: hosting quality, CDN configuration, database queries, server-side rendering time - Fix: upgrade hosting, add CDN, optimize server-side code, enable caching **Is the LCP element an image?** - → Image optimization issue - Check: image format (use WebP/AVIF), image size (serve responsive sizes), lazy loading on LCP image (should NOT be lazy loaded) - Fix: convert to modern formats, add `width`/`height` attributes, use `fetchpriority="high"` on LCP image, preload the LCP image **Is the LCP element text?** - → Font loading issue - Check: custom fonts blocking render, font file size, font-display strategy - Fix: use `font-display: swap` or `optional`, preload critical fonts, subset fonts to used characters **Is render-blocking CSS/JS delaying the LCP?** - Check: large CSS files in `<head>`, synchronous JS before content - Fix: inline critical CSS, defer non-critical CSS, async/defer JS ## CLS Root-Cause Tree CLS measures unexpected layout shifts. Diagnose: **Do images/videos lack dimensions?** - → Browser can't reserve space before loading - Fix: add `width` and `height` attributes to all `<img>` and `<video>` elements, use CSS `aspect-ratio` **Do ads or embeds inject content?** - → Dynamic content pushing existing content down - Fix: reserve space for ad slots with min-height, use `contain-intrinsic-size` for lazy content **Do fonts cause text reflow?** - → FOUT (Flash of Unstyled Text) causes layout shift when custom font loads - Fix: use `font-display: optional` (no swap = no shift), or match fallback font metrics **Does dynamic content insert above the fold?** - → Banners, cookie notices, notifications pushing content - Fix: use overlays instead of inline insertions, or reserve space with fixed-height containers ## INP Root-Cause Tree INP measures responsiveness to user interactions. Diagnose: **Is the main thread blocked by long tasks?** - Check: JavaScript execution time, third-party scripts, large DOM - Fix: break long tasks with `requestIdleCallback` or `setTimeout`, code-split heavy modules **Do event handlers do heavy synchronous work?** - Check: click handlers that trigger large DOM updates, form validation on every keystroke - Fix: debounce inputs, use requestAnimationFrame for visual updates, offload work to web workers **Are third-party scripts competing for the main thread?** - Check: analytics, chat widgets, A/B testing tools, social embeds -