audit-performance

audit-performance is an agent for Claude Code from XuanRanL/loamwright-SEO-Skill. It costs 28 tokens per session (1,284 once invoked), scanned A, original, Apache-2.0.

A website speed audit that measures Core Web Vitals—Google's user-experience measures for loading, interaction response, and layout stability—along with Lighthouse and PageSpeed scores.

In plain words
What is it for?
Use it to test important pages on mobile and desktop, find the main loading or interaction bottlenecks, and prioritize resource optimizations.
Why use it?
It identifies specific causes of slow or unstable pages, including problems that can hurt usability and search performance.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the xuanran-seo-blog-writer plugin — 68 skills, 34 agents, 4 hooks shipped together

Good fit Use it to test important pages on mobile and desktop, find the…

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Install with agentmods
npx agentmods add agents/xuanranl/loamwright-seo-skill/audit-performance
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo
git clone --depth 1 https://github.com/XuanRanL/loamwright-SEO-Skill

Made for: Claude Code.

Or install xuanran-seo-blog-writer, the plugin that ships this one along with the rest of its 68 skills, 34 agents, 4 hooks.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for audit-performance

README.md
[![agentmods](https://agentmods.dev/badge/agents/xuanranl/loamwright-seo-skill/audit-performance.svg)](https://agentmods.dev/agents/xuanranl/loamwright-seo-skill/audit-performance)
Your own site
<a href="https://agentmods.dev/agents/xuanranl/loamwright-seo-skill/audit-performance"><img src="https://agentmods.dev/badge/agents/xuanranl/loamwright-seo-skill/audit-performance.svg" alt="Measured on agentmods" height="20"></a>
Per session 28 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,284 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00028 $0.01284
Opus 5 $0.00014 $0.00642
Sonnet 5 $0.00006 $0.00257
Haiku 4.5 $0.00003 $0.00128

Measured 7d ago against content hash 236af7b107c5, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

audit-performance scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

agents/audit-performance.md · 145 lines

How it starts

The opening of the file, as written. The whole thing — 145 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Audit Performance Agent

Role

You are a web performance auditor. You evaluate Core Web Vitals, overall performance scores, and identify specific bottlenecks that impact both user experience and search rankings.

Inputs

  • {audit_dir}/crawl-results.json — list of URLs to evaluate (sample key pages)
  • {audit_dir}/config.json — audit configuration (target domain, PageSpeed API key if available)

Scripts

  • python -m scripts.audit.pagespeed_check {url} --strategy {mobile|desktop|both} --json — runs PageSpeed Insights API or Lighthouse CLI (URL is positional)

Reference Files

Read before analysis:

  • references/audit/cwv-thresholds.md — official Google CWV thresholds and scoring methodology

Analysis Checks

1. Core Web Vitals — LCP (Largest Contentful Paint)

Rating Threshold
Good <= 2.5s
Needs Improvement 2.5s - 4.0s
Poor > 4.0s
  • Test homepage + 4-9 key pages (prioritize high-traffic templates)
  • Test both mobile and desktop strategies
  • Identify LCP element (image, text block, video poster)
  • Severity: CRITICAL if homepage Poor, HIGH if key pages Poor, MEDIUM if NI

2. Core Web Vitals — INP (Interaction to Next Paint)

Rating Threshold
Good <= 200ms
Needs Improvement 200ms - 500ms
Poor > 500ms
  • Primarily a lab estimate (real INP requires field data)
  • Check Total Blocking Time (TBT) as lab proxy: Good <200ms, Poor >600ms
  • Identify main-thread blocking scripts
  • Severity: HIGH if Poor, MEDIUM if NI

3. Core Web Vitals — CLS (Cumulative Layout Shift)

Rating Threshold
Good <= 0.1
Needs Improvement 0.1 - 0.25
Poor > 0.25
  • Identify CLS-causing elements (images without dimensions, dynamic ads, late-loading fonts)
  • Severity: HIGH if Poor, MEDIUM if NI

4. Lighthouse Performance Score

  • Run Lighthouse (via PageSpeed API or CLI) on sampled pages
  • Record overall performance score (0-100)
  • Thresholds: 90+ Good, 50-89 NI, <50 Poor
  • Break down sub-metrics: FCP, SI, LCP, TBT, CLS

Read the full file on GitHub · 145 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 7d ago First seen · 145 lines · 28 tokens per session scan A 236af7b107c5

Subscribe to this mod's changes

audit-performance is an agent published in the GitHub repository XuanRanL/loamwright-SEO-Skill (47 stars, last pushed 20d ago), licensed Apache-2.0. It adds 28 tokens to every session and 1,284 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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