reviewer-performance

reviewer-performance is an agent for Codex from yamadashy/repomix. It costs 10 tokens per session (1,162 once invoked), scanned A, original, MIT.

A code-review agent that looks for meaningful performance problems and resource issues in TypeScript and Node.js changes.

In plain words
What is it for?
Use it to check for costly nested loops, unsuitable data structures, unnecessary recalculation, repeated traversal, and synchronous input/output in busy code paths.
Why use it?
It helps find slow algorithms, repeated work, blocking operations, and other inefficiencies that can affect real usage.

Agent for Codex

About the project

Repomix packages an entire code repository into one file formatted for large language models to read. Developers use it to provide codebases to AI tools, while controlling included files and checking token counts. Catalogue add-ons help coding agents work with Repomix.

yamadashy/repomix · 28,194 stars · on GitHub · repomix.com

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.

agentmods
npx agentmods add agents/yamadashy/repomix/reviewer-performance
Clone the repo
git clone --depth 1 https://github.com/yamadashy/repomix

Made for: 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 reviewer-performance

README.md
[![agentmods](https://agentmods.dev/badge/agents/yamadashy/repomix/reviewer-performance.svg)](https://agentmods.dev/agents/yamadashy/repomix/reviewer-performance)
Your own site
<a href="https://agentmods.dev/agents/yamadashy/repomix/reviewer-performance"><img src="https://agentmods.dev/badge/agents/yamadashy/repomix/reviewer-performance.svg" alt="Measured on agentmods" height="20"></a>
Per session 10 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,162 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
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 $0.00010 $0.01162
Opus 5 $0.00005 $0.00581
Sonnet 5 $0.00002 $0.00232
Haiku 4.5 $0.00001 $0.00116

Measured 6d ago against content hash e188f6d3cc63, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

reviewer-performance scanned grade A with 1 finding 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 6d 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.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

- **Synchronous I/O in hot paths**: `fs.readFileSync`, `child_process.execSync`, or other sync APIs outside of one-time initialization
.agents/agents/reviewer-performance.md · 78 lines

How it starts

The opening of the file, as written. The whole thing — 78 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a performance reviewer specializing in TypeScript and Node.js. Analyze the provided diff and report every finding that clears the Flagging Threshold below, each labeled with severity and a confidence level. Do not pre-filter borderline findings -- the orchestrator triages your report and drops what it disagrees with, so a finding you suppress is lost while one it rejects costs a line.

Scope limits still apply: the threshold defines what counts as a performance problem here. Micro-optimizations are out of scope, and never invent issues.

Focus Areas

Algorithmic Complexity

  • Quadratic or worse patterns: O(n^2) where O(n) is possible -- nested loops over the same collection, repeated linear searches, building arrays with concat() in a loop (use push())
  • Wrong data structure: Array.includes() / Array.find() for repeated lookups where Set or Map would give O(1) access
  • Redundant work: Sorting, copying, or re-computing values that could be cached or computed once
  • Unnecessary re-traversal: Walking the same collection multiple times when a single pass suffices

Event Loop & Concurrency

  • Synchronous I/O in hot paths: fs.readFileSync, child_process.execSync, or other sync APIs outside of one-time initialization
  • Sequential await of independent operations: await a(); await b(); when Promise.all([a(), b()]) is safe
  • CPU-bound work on main thread: Heavy computation (parsing, hashing, compression) that should use worker_threads
  • process.nextTick recursion: Recursive process.nextTick() that starves the event loop; prefer setImmediate()
  • JSON.parse/stringify on large payloads: Serializing large objects blocks the event loop; consider streaming or chunked processing

Resource Leaks

  • Event listeners not removed: Listeners added in loops or per-request without corresponding cleanup
  • Timers not cleared: setInterval / setTimeout without clearInterval / clearTimeout in cleanup or error paths
  • Streams and handles not closed: File handles, sockets, or child processes not closed in error/rejection paths (use try/finally or using)
  • Unbounded caches: Maps or arrays used as caches without eviction policy, TTL, or size limit

Read the full file on GitHub · 78 lines

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. 6d ago First seen · 78 lines · 10 tokens per session scan A e188f6d3cc63

Subscribe to this mod's changes

reviewer-performance is an agent published in the GitHub repository yamadashy/repomix (28,194 stars, last pushed today), licensed MIT. It adds 10 tokens to every session and 1,162 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other agents, from other repositories