web-performance

web-performance is a skill for Claude Code, Codex from chadixearth/graphyloop. It costs 82 tokens per session (1,400 once invoked), scanned A, original, MIT.

A guide for measuring and improving how quickly web pages and apps load and respond.

In plain words
What is it for?
Use it to investigate slow pages, large bundles, poor Lighthouse scores, animation or third-party-script costs, and performance budgets before release.
Why use it?
It replaces guesswork with measurements such as loading time, interaction delay, layout movement, server response time, and JavaScript size.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to investigate slow pages, large bundles, poor Lighthouse scores, animation or third-party-script costs, and performance budgets before release.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/chadixearth/graphyloop/web-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.

Any agent
npx skills add chadixearth/graphyloop --skill web-performance
Clone the repo
git clone --depth 1 https://github.com/chadixearth/graphyloop

Made for: Claude Code, Codex.

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 web-performance

README.md
[![agentmods](https://agentmods.dev/badge/skills/chadixearth/graphyloop/web-performance/github.svg)](https://agentmods.dev/skills/chadixearth/graphyloop/web-performance)
Your own site
<a href="https://agentmods.dev/skills/chadixearth/graphyloop/web-performance"><img src="https://agentmods.dev/badge/skills/chadixearth/graphyloop/web-performance/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for web-performance

Your own site · 80×15
<a href="https://agentmods.dev/skills/chadixearth/graphyloop/web-performance"><img src="https://agentmods.dev/badge/skills/chadixearth/graphyloop/web-performance.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 82 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,400 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00082 $0.01400
Opus 5 $0.00041 $0.00700
Sonnet 5 $0.00016 $0.00280
Haiku 4.5 $0.00008 $0.00140

Measured 5d ago against content hash c616cde1e7ae, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

web-performance scanned grade A with 1 finding 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 5d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- Compression on (brotli) — verify with `curl -sI -H 'accept-encoding: br'`.
skills/web-performance/SKILL.md · 106 lines

How it starts

The opening of the file, as written. The whole thing — 106 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Web performance (front of the stack)

Frontend performance work goes wrong in one way: guessing. Someone memoizes a component while a 900 KB font and a synchronous third-party script own the critical path. Measure, fix the biggest item, measure again — and keep the number.

When to activate

  • "It's slow", "LCP regressed", "the bundle doubled", "the list janks", low Lighthouse/PageSpeed score, a CI budget failing.
  • Before shipping a new page, dashboard, or heavy dependency.
  • After adding an animation library, chart library, map, video, or analytics tag.

Step 1 — baseline (never skip)

Record numbers before touching code; without a baseline there is no win to claim.

npx lighthouse http://127.0.0.1:PORT --preset=desktop --quiet --output=json --output-path=./.perf/base.json
npx lighthouse http://127.0.0.1:PORT --quiet   # default = mobile throttling, the honest one
ANALYZE=true npm run build        # next: @next/bundle-analyzer
npx vite-bundle-visualizer        # vite
npx source-map-explorer 'dist/assets/*.js'

Capture: LCP, INP (replaces FID), CLS, TTFB, total JS transferred, largest chunks, request count, and the field data if you have RUM. Note whether the run is throttled — an unthrottled localhost number is not a result.

Targets (75th percentile, mobile) — the three Core Web Vitals plus TTFB, which is a diagnostic for the first of them rather than a vital itself: LCP ≤ 2.5 s · INP ≤ 200 ms · CLS ≤ 0.1 · TTFB ≤ 0.8 s, and a JS budget you write down (e.g. ≤ 170 KB gzipped for the initial route).

Step 2 — fixes, ordered by payoff

LCP (usually an image or a slow server)

  • Find the LCP element in the Lighthouse trace before optimizing anything.
  • Hero image: correct format (AVIF/WebP), correct dimensions, priority / fetchpriority="high", preload the actual file; every other image loading="lazy"
    • decoding="async".
  • Kill render-blocking: no @import chains, inline critical CSS, defer scripts, preconnect to the font/API origin, self-host fonts with font-display: swap and subset them (unicode-range). One variable font beats four weights.
  • Server side: cache the data the first paint needs, stream (RSC/Suspense) instead of awaiting everything, and check TTFB separately — a 1.5 s TTFB is a backend bug (query plan, N+1, cold start), not a CSS problem.

Read the full file on GitHub · 106 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. 5d ago First seen · 106 lines · 82 tokens per session scan A c616cde1e7ae

Subscribe to this mod's changes

web-performance is a skill published in the GitHub repository chadixearth/graphyloop (2 stars, last pushed 23d ago), licensed MIT. It adds 82 tokens to every session and 1,400 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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