Borrowing it
Nothing to install: this file belongs to Caspian-Sun/claude-code-workflow. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/Caspian-Sun/claude-code-workflow/main/.claude/skills/ext-perf-audit/SKILL.mdgit clone --depth 1 https://github.com/Caspian-Sun/claude-code-workflowWrote 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.
[](https://agentmods.dev/skills/caspian-sun/claude-code-workflow/ext-perf-audit)<a href="https://agentmods.dev/skills/caspian-sun/claude-code-workflow/ext-perf-audit"><img src="https://agentmods.dev/badge/skills/caspian-sun/claude-code-workflow/ext-perf-audit/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.
<a href="https://agentmods.dev/skills/caspian-sun/claude-code-workflow/ext-perf-audit"><img src="https://agentmods.dev/badge/skills/caspian-sun/claude-code-workflow/ext-perf-audit.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00054 | $0.00692 |
| Opus 5.5 | $0.00022 | $0.00277 |
| Sonnet 5.5 | $0.00011 | $0.00138 |
| Haiku 4.5 | $0.00005 | $0.00069 |
Grade A, and why
ext-perf-audit 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 2mo 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.
How it starts
The opening of the file, as written. The whole thing — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.
ext-perf-audit — Performance Audit
You are now a frontend performance optimization expert. Perform a performance audit on the specified component / page / module.
Execution Approach
Run scripts to gather data first, then use AI for static analysis. Scripts handle measurement; AI handles pattern recognition.
Step 1: Build Artifact Analysis (if dist exists)
bash .claude/skills/ext-perf-audit/scripts/bundle-size.sh
Script output:
- Total size + chunks sorted by size
- List of JS files larger than 100KB
- List of asset files larger than 500KB (images / fonts)
AI identifies:
- Warnings for any single chunk > 500KB
- Images not compressed / not converted to WebP
- No route-level code splitting (e.g., an oversized
index.*.js)
Step 2: Dependency Size Quick Scan
bash .claude/skills/ext-perf-audit/scripts/heavy-deps.sh
The script lists the top 20 largest packages in node_modules. AI cross-references the "Common Bundle Killers" section in references/perf-checklist.md and provides recommendations.
Step 3: Static Code Scan (AI reads source)
Check the directory specified by $ARGUMENTS across the 5 dimensions in references/perf-checklist.md:
- Bundle size — full-library imports / duplicate dependencies / console.log / missing lazy loading
- Rendering performance — missing memo/useMemo/useCallback / missing keys / new references created in render path / state hoisted too high / JS doing CSS's job
- Network performance — serial requests that could be parallel / missing caching / image formats / missing prefetch
- Memory — useEffect missing cleanup / closures holding large objects / no virtual scrolling
- Initial load — blocking the critical path / missing Skeleton / waterfall requests
Output Format
🔴 Critical (impacts user experience):
- [file:line] Issue description
Impact: Estimated impact (e.g. +800ms on initial load / bundle +400KB)
Fix: Specific solution + code example
🟡 Moderate (worth optimizing):
- [file:line] Issue description
Fix: Solution
🔵 Suggestion (nice to have):
- [file:line] Issue description
📊 Overall: X/10, one-sentence summary
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.
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.
- 2mo ago First seen · 79 lines · 54 tokens per session scan A da12510abb79
ext-perf-audit is a skill published in the GitHub repository Caspian-Sun/claude-code-workflow (10 stars, last pushed 2mo ago), licensed MIT. It adds 54 tokens to every session and 692 once invoked, about $0.0002 per session on Opus 5.5. 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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