perf

perf is a skill for Claude Code, Codex from Dragoon0x/dragoon-skills. It costs 114 tokens per session (376 once invoked), scanned A, original, MIT.

A web-performance checker that finds common problems in source code and can summarize a Lighthouse JSON report. Lighthouse is a tool that measures website speed and related user-experience signals.

In plain words
What is it for?
Use it before launch or after a Lighthouse run to decide which performance fixes to address first.
Why use it?
It highlights issues such as oversized images, layout shifts, and blocking scripts, and ranks Lighthouse findings by possible time savings. It does not run Lighthouse itself.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: reads .claude/ paths.

Good fit Use it before launch or after a Lighthouse run to decide which performance fixes to address first.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/dragoon0x/dragoon-skills/perf
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 Dragoon0x/dragoon-skills --skill perf
Clone the repo
git clone --depth 1 https://github.com/Dragoon0x/dragoon-skills

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 perf

README.md
[![agentmods](https://agentmods.dev/badge/skills/dragoon0x/dragoon-skills/perf/github.svg)](https://agentmods.dev/skills/dragoon0x/dragoon-skills/perf)
Your own site
<a href="https://agentmods.dev/skills/dragoon0x/dragoon-skills/perf"><img src="https://agentmods.dev/badge/skills/dragoon0x/dragoon-skills/perf/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 perf

Your own site · 80×15
<a href="https://agentmods.dev/skills/dragoon0x/dragoon-skills/perf"><img src="https://agentmods.dev/badge/skills/dragoon0x/dragoon-skills/perf.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 114 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 376 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 $0.00114 $0.00376
Opus 5 $0.00057 $0.00188
Sonnet 5 $0.00023 $0.00075
Haiku 4.5 $0.00011 $0.00038

Measured 9d ago against content hash 91326491744d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

perf 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 9d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/perf.js), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/perf/SKILL.md · 41 lines

What it actually says

/perf

Two halves: static hints from your codebase, and parsing of Lighthouse JSON reports.

When to use

  • The user wants to audit web performance
  • After running Lighthouse, to surface the most impactful audits
  • Before launch, to catch image and script issues early

Static rules

  • perf-001 large-image (>500KB) (medium)
  • perf-002 img-missing-dimensions causes CLS (low)
  • perf-003 img-without-loading-lazy below the fold (low)
  • perf-004 sync-script-tag blocks parsing (medium)

Lighthouse ingestion

npx lighthouse https://example.com --output json --output-path lh.json
dragoon perf --lighthouse lh.json

Output: scores per category, core web vitals (LCP/CLS/TBT/INP/FCP/SI), and the top 6 failing audits ranked by ms savings.

Run it

dragoon perf                                # static only
dragoon perf --lighthouse lh.json           # add lighthouse summary
dragoon perf --severity medium              # filter
dragoon perf --json                         # CI mode
Files

What ships with it

1 file 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. 9d ago First seen · 41 lines · 114 tokens per session scan A 91326491744d

Subscribe to this mod's changes

perf is a skill published in the GitHub repository Dragoon0x/dragoon-skills (4 stars, last pushed 4mo ago), licensed MIT. It adds 114 tokens to every session and 376 once invoked, about $0.0006 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 2026-08-31.

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