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Agent skill

Web Perf

by elithrar in elithrar/dotfiles

Diagnose page-load and interaction performance using browser traces, network evidence, and source code.

MITAuto-check passedFrontend & Design

Install Web Perf

skills CLI
$ npx skills add elithrar/dotfiles --skill web-perf -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install elithrar/dotfiles web-perf --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/elithrar/dotfiles.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/web-perf .claude/skills/web-perf && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
web-perf
GitHub stars
202
Token cost
~721 tokens
SKILL.md length
361 words
Files
3 (incl. references)
Skills in repo
12
Repo updated
First seen
Licence
MIT

At a glance

Diagnose page-load and interaction performance using browser traces, network evidence, and source code.

  • Core Web Vitals
  • SKILL.md covers Choose the evidence path, Diagnose and Validate and report
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
  • Layout-shift investigations

What it does

Web Perf is an agent skill from elithrar/dotfiles. Diagnose page-load and interaction performance using browser traces, network evidence, and source code. Use for site-speed, Lighthouse, Core Web Vitals, or layout-shift investigations; a general accessibility audit is separate.

Its SKILL.md is about 720 tokens, which your agent loads only when the skill is triggered. The skill folder holds 4 other files, including reference files (for example `evals/evals.json` and `references/devtools.md`).

It sits in Frontend & Design, covering Web performance and Accessibility. The repository describes itself as: dotfiles for my macOS & Linux environments ⌨️. The licence is MIT.

When your agent uses it

  • Core Web Vitals
  • Layout-shift investigations
  • A general accessibility audit is separate

Example prompts

  • “/web-perf”

What it can do on your machine

Read from SKILL.md and the folder at commit 26e8a4b. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Web Perf loads about 721 tokens when it runs, and up to ~1.3k if it reads all its reference files. Until then it costs about 59 tokens; SKILL.md has 361 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~59
When it runs · the whole SKILL.md, loaded when a task matches
~721
With references · SKILL.md plus every file in references/, read only if the agent opens them
~1.3k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from elithrar/dotfiles at commit 26e8a4b, republished under its MIT licence (© elithrar). 361 words, ~721 tokens.

Download SKILL.mdSave it as .claude/skills/web-perf/SKILL.md (or your agent's skills folder). This skill also uses 2 other files; get the full folder from GitHub.
name
web-perf
description
Diagnose page-load and interaction performance using browser traces, network evidence, and source code. Use for site-speed, Lighthouse, Core Web Vitals, or layout-shift investigations; a general accessibility audit is separate.

Web performance investigation

Identify the target page, reported symptom, and relevant device conditions. For audit requests, report findings. For optimization or fix requests, implement the supported changes and validate their effect within the requested scope.

Choose the evidence path

Inspect the available browser and profiling tools before calling them. Prefer Chrome DevTools traces when available; read references/devtools.md for trace and network investigation. Use the installed tool schemas rather than assuming example parameters match the current version.

If that MCP server is unavailable, use existing trace or Lighthouse artifacts, another available profiler, or relevant source code. Complete the analysis those sources support and state what could not be measured. Missing profiling tools do not justify stopping source inspection or forcing an MCP installation.

Diagnose

Record the page/build, viewport, device or emulation, network/CPU throttling, cache state, and interactions relevant to the result. Reloading alone does not establish a cold cache. Keep mobile and desktop observations distinct.

Separate field Core Web Vitals from laboratory measurements. A load-only trace does not establish INP; TBT is a diagnostic lab metric, not a substitute INP measurement. Use the current metric definitions when assigning ratings, and label missing measurements as unavailable.

Follow the bottleneck from trace insight to request, element, or source path. Inspect the relevant LCP phases, layout-shift participants, long tasks, late resource discovery, or cache headers. Confirm ownership and use before recommending removal, especially for third-party scripts or resources used only in later interactions. Zero estimated savings is not evidence of a material problem, but one trace cannot prove a resource is never useful.

Show full SKILL.md (102 more words)Show less

Validate and report

Prioritize findings by observed user impact and confidence. Distinguish measured values, tool estimates, and unmeasured hypotheses; avoid promising additive savings from overlapping insights.

For a fix, compare the affected behavior under equivalent conditions. Repeat measurements when variance or the size of the claimed improvement warrants it. Broaden testing only for an unresolved regression risk or a project gate, then finish.

Report the measured symptom, its supported cause, the concrete fix or recommendation, and the relevant verification limit. Add a metric table when several measurements help comparison. Do not expand a performance request into a mandatory accessibility or whole-codebase audit.

© elithrar, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 2 other files (references) in .agents/skills/web-perf of elithrar/dotfiles.

  • SKILL.md
  • evals/evals.json
  • references/devtools.md

Open the folder on GitHubat commit 26e8a4b

Compare with similar skills

Web Perf next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Web Perf compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Web Perf this skillelithrar/dotfiles202—~721Automated safety check: PassMIT
Web Quality Auditaddyosmani/web-quality-skills2.9k—~2.6kAutomated safety check: PassMIT
Web Quality Auditmidudev/100cosas.dev1143 repos~1.7kAutomated safety check: PassMIT
Optimize Loadtextura-agency/next16-claude-starter132—~4.6kAutomated safety check: NotesUnlicense
Accessibilityericrisco/rsc-harness167—~3.4kAutomated safety check: PassMIT
Accessibility Checkmakifbaysal/tasktrooper109—~1.1kAutomated safety check: PassApache-2.0

Similar skills

  • Web Quality Audit

    addyosmani/web-quality-skills

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    2.9k GitHub stars~2.6k tokensUpdated 1 mo ago
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  • Web Quality Audit

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    114 GitHub starsUsed in 3 repos~1.7k tokens
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  • Accessibility

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    167 GitHub stars~3.4k tokensUpdated today
    Frontend & DesignAuto-check passed

  • Accessibility Check

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  • Best Practices

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Categories

Questions about Web Perf

What does Web Perf do?

Diagnose page-load and interaction performance using browser traces, network evidence, and source code. Web Perf is an agent skill from elithrar/dotfiles. Diagnose page-load and interaction performance using browser traces, network evidence, and source code.

When should I use Web Perf?

Web Perf fits situations like: core Web Vitals; layout-shift investigations; A general accessibility audit is separate.

How do I install Web Perf in Claude Code?

Run `npx skills add elithrar/dotfiles --skill web-perf -a claude-code`. Or copy the skill folder (.agents/skills/web-perf in elithrar/dotfiles) into .claude/skills/web-perf in your project. Claude Code loads it when a task matches its description.

How do I install Web Perf in Codex?

Run `npx skills add elithrar/dotfiles --skill web-perf -a codex`. Or copy the skill folder (.agents/skills/web-perf in elithrar/dotfiles) into .agents/skills/web-perf in your project. Codex loads it when a task matches its description.

Can I use Web Perf in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add elithrar/dotfiles --skill web-perf -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/web-perf, .gemini/skills/web-perf, .github/skills/web-perf and .opencode/skills/web-perf in your project.

What does Web Perf need to run?

SKILL.md names no scripts, command-line tools or credentials: Web Perf is instructions for the agent only.

Does Web Perf access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Web Perf safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Web Perf use?

Web Perf is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Web Perf use?

About 721 tokens (SKILL.md is roughly 2.9k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 552 tokens, read only when the agent opens those files.

What are the alternatives to Web Perf?

Skills that share tags, products or a category with Web Perf: Web Quality Audit (addyosmani/web-quality-skills, 2.9k stars), Web Quality Audit (midudev/100cosas.dev, 114 stars), Optimize Load (textura-agency/next16-claude-starter, 132 stars) and Accessibility (ericrisco/rsc-harness, 167 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Web Perf?

elithrar (a GitHub user) maintains it in elithrar/dotfiles, which has 202 GitHub stars. The repository holds 12 skills in this directory. The repository was last updated on October 7, 2026.

Source: elithrar/dotfiles on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.