Audit Speed
- 2.3k installs
- 17 repo stars
- Updated February 27, 2026
- calm-north/seojuice-skills
audit-speed is an SEOJuice skill for deep Core Web Vitals audits with root-cause trees and prioritized speed fixes.
About
audit-speed performs deep Core Web Vitals audits with threshold tables for LCP, CLS, INP, FCP, and TTFB rated good, needs improvement, or poor. Before starting, gather target pages, existing Lighthouse or PageSpeed data, tech stack, and constraints like immovable third-party scripts. LCP diagnosis branches on slow TTFB, image LCP elements needing WebP, fetchpriority, and no lazy-load on LCP, text LCP font loading issues, or render-blocking CSS and JS. CLS trees cover missing image dimensions, ad embed shifts, font reflow, and dynamic above-fold insertions with overlay or reserved-space fixes. INP trees address main-thread long tasks, heavy event handlers, and third-party script contention with deferral strategies. Resource analysis benchmarks total page weight under 1.5 MB, JS under 300 KB compressed, and CSS under 100 KB. Output format tables metrics with root causes, resource breakdown, priority fixes by impact, and quick wins checklists. SEOJuice MCP page-audit and CWV Impact Calculator links support measurement follow-up.
- Core Web Vitals threshold tables for LCP, CLS, INP, FCP, and TTFB.
- LCP, CLS, and INP root-cause decision trees with specific fixes.
- Resource weight benchmarks for HTML, CSS, JS, images, fonts, third-party.
- Priority fixes ordered by impact with quick wins checklist output.
- SEOJuice MCP page-audit integration for live CWV scores.
Audit Speed by the numbers
- 2,324 all-time installs (skills.sh)
- +13 installs in the week ending Aug 5, 2026 (Skillselion tracking)
- Ranked #255 of 1,879 Marketing & SEO skills by installs in the Skillselion catalog
- Security screen: LOW risk (skills.sh audit)
- Data as of Aug 5, 2026 (Skillselion catalog sync)
audit-speed capabilities & compatibility
- Capabilities
- cwv threshold rating for five core metrics · lcp cls inp root cause decision trees · resource breakdown with size benchmarks · priority fix ordering by estimated impact · quick wins checklist generation
- Works with
- chrome
- Use cases
- seo · web design
- Runs
- Runs locally
- Pricing
- Freemium
What audit-speed says it does
LCP image (should NOT be lazy loaded)
Total page weight under 1.5 MB is good
For broader technical SEO issues, see diagnose-seo.
npx skills add https://github.com/calm-north/seojuice-skills --skill audit-speedAdd your badge
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| Installs | 2.3k |
|---|---|
| repo stars | ★ 17 |
| Security audit | 3 / 3 scanners passed |
| Last updated | February 27, 2026 |
| Repository | calm-north/seojuice-skills ↗ |
Why is my page slow and which Core Web Vitals fixes will have the highest SEO impact?
Audit Core Web Vitals and page speed with LCP, CLS, INP root-cause trees and prioritized fix recommendations.
Who is it for?
Teams diagnosing LCP, CLS, or INP failures on key landing pages before or after launch.
Skip if: Skip for broad technical SEO indexability issues covered by diagnose-seo instead.
When should I use this skill?
User asks about page speed, Core Web Vitals, Lighthouse scores, LCP, CLS, INP, or performance optimization.
What you get
Metric-rated audit with root causes, resource breakdown, and ordered priority fixes plus quick wins.
- CWV threshold report
- Root-cause analysis tree
- Prioritized optimization recommendations
By the numbers
- Encodes CWV thresholds: LCP good <2.5s, CLS good <0.1
- Skill metadata version 1.0.0
Files
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/heightattributes, usefetchpriority="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: swaporoptional, 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
widthandheightattributes to all<img>and<video>elements, use CSSaspect-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-sizefor 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
requestIdleCallbackorsetTimeout, 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
- Fix: defer loading until after interaction, use
loading="lazy"for embeds, consider removing low-value scripts
Resource Analysis
Break down the total page weight:
| Resource Type | Size | Assessment | Action |
|---|---|---|---|
| HTML | [x] KB | [ok/large] | Compress, reduce inline styles/scripts |
| CSS | [x] KB | [ok/large] | Remove unused CSS, minify, critical CSS extraction |
| JavaScript | [x] KB | [ok/large] | Code-split, tree-shake, defer non-critical |
| Images | [x] KB | [ok/large] | Modern formats, responsive sizes, lazy load below fold |
| Fonts | [x] KB | [ok/large] | Subset, limit families/weights, preload critical |
| Third-party | [x] KB | [ok/large] | Audit necessity, defer, self-host if possible |
Benchmarks:
- Total page weight under 1.5 MB is good
- JavaScript under 300 KB (compressed) for most sites
- CSS under 100 KB (compressed)
- First-party fonts under 100 KB
Output Format
Speed Audit: [URL or domain]
Core Web Vitals
| Metric | Value | Rating | Root Cause |
|---|---|---|---|
| LCP | [value] | Good / Needs Improvement / Poor | [identified cause] |
| CLS | [value] | ... | ... |
| INP | [value] | ... | ... |
| FCP | [value] | ... | ... |
| TTFB | [value] | ... | ... |
Resource Breakdown [Table from Resource Analysis]
Priority Fixes
For each failing metric, ordered by impact:
1. [Metric]: [Root cause]
- Current: [value]
- Target: [threshold]
- Fix: [specific action]
- Estimated impact: [high/medium/low]
2. ...
Quick Wins List optimizations that require minimal effort:
- [ ] Add
width/heightto images - [ ] Set
fetchpriority="high"on LCP image - [ ] Defer non-critical JavaScript
- [ ] ...
---
Pro Tip: Use the free CWV Impact Calculator
to estimate the traffic impact of fixing Core Web Vitals, and the
Critical CSS Generator to extract
above-the-fold CSS. SEOJuice MCP users can run /seojuice:page-audit [domain] [url] forinstant CWV scores, Lighthouse data, and resource breakdowns.
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Pick audit-speed over general SEO skills when the bottleneck is measurable page-speed metrics and Core Web Vitals rather than crawlability or content indexing.
FAQ
Should the LCP image be lazy loaded?
No. LCP images should not be lazy loaded; use fetchpriority high and preload instead.
What total page weight is considered good?
Under 1.5 MB total page weight is the documented good benchmark.
Where do I start without existing data?
Run Google PageSpeed Insights on key URLs to gather initial Lighthouse scores.
Is Audit Speed safe to install?
skills.sh reports 3 of 3 security scanners passed. Review the Security Audits panel on this page before installing in production.