app-performance-engineer

app-performance-engineer is an agent for Claude Code from FluxonLab/Skillry. It costs 51 tokens per session (717 once invoked), scanned A, original, no licence file.

An agent that measures and improves application performance across web pages and backend services. It covers page-speed budgets, Core Web Vitals, server latency, flame graphs, caching, and memory or resource leaks, then makes focused verified changes.

In plain words
What is it for?
Use it to investigate frontend speed, backend response times, processing hotspots, caching, and memory or resource leaks.
Why use it?
It helps find the cause of slow or resource-heavy software and confirm that changes improve it safely.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the skillry-performance-and-cost plugin — 2 skills, 2 agents shipped together

Good fit Use it to investigate frontend speed, backend response times, processing hotspots, caching, and memory or resource leaks.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/fluxonlab/skillry/app-performance-engineer
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.

Clone the repo
git clone --depth 1 https://github.com/FluxonLab/Skillry

Made for: Claude Code.

Or install skillry-performance-and-cost, the plugin that ships this one along with the rest of its 2 skills, 2 agents.

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 app-performance-engineer

README.md
[![agentmods](https://agentmods.dev/badge/agents/fluxonlab/skillry/app-performance-engineer/github.svg)](https://agentmods.dev/agents/fluxonlab/skillry/app-performance-engineer)
Your own site
<a href="https://agentmods.dev/agents/fluxonlab/skillry/app-performance-engineer"><img src="https://agentmods.dev/badge/agents/fluxonlab/skillry/app-performance-engineer/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 app-performance-engineer

Your own site · 80×15
<a href="https://agentmods.dev/agents/fluxonlab/skillry/app-performance-engineer"><img src="https://agentmods.dev/badge/agents/fluxonlab/skillry/app-performance-engineer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 51 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 717 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 unknown 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 $0.00051 $0.00717
Opus 5.5 $0.00020 $0.00287
Sonnet 5.5 $0.00010 $0.00143
Haiku 4.5 $0.00005 $0.00072

Measured 27d ago against content hash 37386268eb07, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

app-performance-engineer 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 27d 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.

plugins/performance-and-cost/agents/app-performance-engineer.md · 61 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

Read it on GitHub

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. 27d ago First seen · 61 lines · 51 tokens per session scan A 37386268eb07

Subscribe to this mod's changes

app-performance-engineer is an agent published in the GitHub repository FluxonLab/Skillry (6 stars, last pushed 24d ago), with no licence file. It adds 51 tokens to every session and 717 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 2026-09-20.

Related

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