Borrowing it
Nothing to install: this file belongs to adobecom/da-express-milo. 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/adobecom/da-express-milo/stage/.claude/skills/performance-testing/SKILL.mdgit clone --depth 1 https://github.com/adobecom/da-express-miloWrote 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/adobecom/da-express-milo/performance-testing)<a href="https://agentmods.dev/skills/adobecom/da-express-milo/performance-testing"><img src="https://agentmods.dev/badge/skills/adobecom/da-express-milo/performance-testing/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/adobecom/da-express-milo/performance-testing"><img src="https://agentmods.dev/badge/skills/adobecom/da-express-milo/performance-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00176 | $0.05851 |
| Opus 5.5 | $0.00070 | $0.02340 |
| Sonnet 5.5 | $0.00035 | $0.01170 |
| Haiku 4.5 | $0.00018 | $0.00585 |
Grade A, and why
performance-testing 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 1mo 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 — 424 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Performance Testing
This skill covers performance testing for Express pages. Today it has one mode — LCP comparison — with room to grow into others (a single-page report, other Core Web Vitals like CLS, network-waterfall analysis with improvement suggestions) without becoming a different skill: they'd all share the same device/throttling setup and the same kind of trigger phrasing ("check performance," "is this page fast"), so they belong together rather than splintered across skills that duplicate the underlying plumbing.
LCP comparison automates a manual Chrome DevTools workflow: measure Largest Contentful Paint for a test URL and a control URL under identical mobile throttling, repeat several times each, average the results, and report the difference with a plain verdict (improved / regressed / no meaningful change).
It replaces this hand workflow: undock DevTools → emulate Moto G Power → set CPU 4× + network throttling in the Performance panel → record a reload 5× per URL → average the LCPs → compare. The bundled Playwright script reproduces those conditions and does the runs and math for you.
The scripts/ directory is split so future modes don't duplicate this: lib/ measure.mjs loads one URL under given conditions and returns metrics (this is
where a future CLS/network capture would extend, not fork), lib/stats.mjs is
the metric-agnostic confidence-interval math, and compare.mjs is the thin CLI
that wires them together for the two-URL comparison. A future report.mjs
(single-page mode) would reuse both lib files rather than duplicate them.
When to use it
Trigger on any request to compare load performance / LCP between two pages — branch vs prod, preview vs published, before vs after a change, or two local branches that haven't been deployed anywhere yet — or to reproduce PSI mobile numbers locally.
Interactive workflow — run this yourself, don't just hand back commands
When a user invokes this skill, drive the whole thing conversationally. Don't dump shell commands and leave the user to run them — ask what you need, then execute every step (including standing up local dev servers, if needed) and report the result.
What ships with it
5 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.
- 1mo ago First seen · 424 lines · 176 tokens per session scan A fa9179017a1c
performance-testing is a skill published in the GitHub repository adobecom/da-express-milo (6 stars, last pushed yesterday), licensed Apache-2.0. It adds 176 tokens to every session and 5,851 once invoked, about $0.0007 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 2026-09-11.
performance-testing compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| performance-testingadobecom/da-express-milo | Skill | 6 | yesterday | Apache-2.0 | A | 176 | Claude Code |
| imagegenopenai/codex | Skill | 133k | yesterday | Apache-2.0 | A | 113 | Codex |
| playwright-climicrosoft/playwright | Skill | 99k | yesterday | Apache-2.0 | A | 19 | Claude Code |
| local-ai-agentsmicrosoft/ai-agents-for-beginners | Skill | 79k | 4d ago | MIT | A | 200 | Claude Code, Codex |
| systematic-debuggingobra/superpowers | Skill | 313k | 3d ago | MIT | A | 21 | Claude Code |
| next-cache-components-adoptionvercel/next.js | Skill | 143k | yesterday | MIT | A | 95 | Claude Code |
| next-partial-prefetching-adoptionvercel/next.js | Skill | 143k | yesterday | MIT | A | 103 | Claude Code |