optimize-load

optimize-load is a skill for Claude Code from textura-agency/next16-claude-starter. It costs 194 tokens per session (5,036 once invoked), scanned A, original, Unlicense.

A web-page performance and quality workflow using Lighthouse, Google's tool for auditing websites. It checks performance, accessibility, common web practices, and search-engine basics on laptop, tablet, and mobile layouts.

In plain words
What is it for?
It is for finding and fixing slow loading, layout shifts, blocking resources, accessibility issues, broken links, and related page problems.
Why use it?
It replaces guesswork with a repeatable audit, targeted fixes, and a new measurement showing whether each change helped.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is node tools/qa/lighthouse.mjs --url http://localhost:3000/ --runs 3 # people, mobile + desktop.

Good fit It is for finding and fixing slow loading, layout shifts, blocking resources, accessibility issues, broken links, and related page problems.

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Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/textura-agency/next16-claude-starter
agentmods
npx agentmods add skills/textura-agency/next16-claude-starter/optimize-load

Made for: Claude Code.

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 optimize-load

README.md
[![agentmods](https://agentmods.dev/badge/skills/textura-agency/next16-claude-starter/optimize-load/github.svg)](https://agentmods.dev/skills/textura-agency/next16-claude-starter/optimize-load)
Your own site
<a href="https://agentmods.dev/skills/textura-agency/next16-claude-starter/optimize-load"><img src="https://agentmods.dev/badge/skills/textura-agency/next16-claude-starter/optimize-load/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 optimize-load

Your own site · 80×15
<a href="https://agentmods.dev/skills/textura-agency/next16-claude-starter/optimize-load"><img src="https://agentmods.dev/badge/skills/textura-agency/next16-claude-starter/optimize-load.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 194 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,036 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 $0.00194 $0.05036
Opus 5.5 $0.00078 $0.02014
Sonnet 5.5 $0.00039 $0.01007
Haiku 4.5 $0.00019 $0.00504

Measured 11d ago against content hash 09d4a2f3e8ea, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

optimize-load 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 11d 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.

`origin-sync.ts` after hydration. Fetch the deployed `og:image` and curl it:
.claude/skills/optimize-load/SKILL.md · 314 lines

How it starts

The opening of the file, as written. The whole thing — 314 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Get the page into the green

Lighthouse, two form factors (plus tablet when it matters), four categories, two audiences (people and the robot form), then fix and prove it. Rewritten from optimisation passes on ~50 production sites built from this starter; each lever says whether it is a rule (held on ≥ 3 sites) or observed (1–2). Before fixing, read obsidian/knowledge/fix-catalog.md and obsidian/knowledge/pitfalls.md.

The bar (reached on every one of those sites): Performance ≥ 90 on mobile and desktop; Accessibility, Best Practices and SEO = 100 on both, for people and for the robot form. 100 on the last three is reachable without changing the design — the classic "axe caught a fade mid-way" flake is fixable (§3). Don't chase Performance from 96 to 100; do chase an A11y 96.

Scope. This skill owns the load: navigation to settled. Scroll jank after load is optimize-performance — Lighthouse never scrolls. A WebGL scene: run optimize-3d-scene first. Real-phone behaviour Lighthouse can't see (iOS toolbar, 120 Hz, menus): mobile-device-qa.

The loop

Build → audit (people + robot, mobile + desktop) → attribute → fix one thing → re-audit. Never report a score you did not re-measure.

0. Rules of measurement

Ignoring these produces confident wrong answers. Each one cost real time.

  1. Audit the build, never next dev. yarn build && yarn start. Kill the old server by port first (next start runs as next-server), and start the new one only if the build succeeded — a failed build serves the previous .next, and the A/B compares the old build with itself.
  2. Median of ≥ 3 runs; 5 before calling a regression. On one unchanged build LCP swung 2.7 → 4.6 s and CLS 0 → 0.18. Lantern can simulate the same preloader-gated LCP at 0.85 s or 4.6 s run to run (one live site scored 89 / 90 / 68 / 90 / 68 in one sitting) — compare metrics → observedLargestContentfulPaint too.
  3. People and robot are different pages. The starter's proxy serves bots — and Lighthouse's default UA, and PageSpeed Insights — the robot form (references/robot-path.md). A people run needs a plain Chrome UA. Audit both; the robot form is what Google and PSI score.
  4. Localhost is a floor, not the record. One site's mobile LCP was 4.8 s locally and 31 s on its real host (11 MB of raw PNGs Lantern only charged on a real network). The other way round too: on asset-heavy pages localhost over HTTP/1.1 bills ~4–6 extra LCP points. Judge local A/Bs by deltas and TBT; take the record on the deployed URL (--url https://…).
  5. A shared or busy machine moves TBT 2×. Interleave A/B arms (old, new, old, new) so both see the same load; note sysctl -n vm.loadavg. Build the baseline from a git worktree of the base branch, never by copying .next/.
  6. Change one thing at a time, and test the hypothesis first. The opening loader was the obvious suspect for a 4 s LCP; removing it entirely moved TBT 20 ms and made two profiles worse.

Read the full file on GitHub · 314 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 11d ago Changed · +165 lines · +24 tokens per session 09d4a2f3e8ea
  2. 29d ago First seen · 149 lines · 170 tokens per session scan A 455e3b39b68e

Subscribe to this mod's changes

optimize-load is a skill published in the GitHub repository textura-agency/next16-claude-starter (137 stars, last pushed 3d ago), licensed Unlicense. It adds 194 tokens to every session and 5,036 once invoked, about $0.0008 per session on Opus 5.5. 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 2026-09-19.

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