performance-reviewer

performance-reviewer is an agent for Claude Code from tmchow/tmc-marketplace. It costs 54 tokens per session (764 once invoked), scanned A, original, MIT.

A code-review specialist that checks changes affecting database queries, data-processing loops, caches, and input/output for runtime and scaling problems.

In plain words
What is it for?
Use it to find repeated database queries, missing pagination, growing memory use, expensive work inside loops, and blocking operations in asynchronous code.
Why use it?
It helps catch code that works on small test data but becomes slow or uses too much memory in production.

Agent for Claude Code

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

Part of the iterative-engineering plugin — 12 skills, 18 agents shipped together

Good fit Use it to find repeated database queries, missing pagination, growing memory use, expensive work inside loops, and blocking operations in asynchronous code.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/tmchow/tmc-marketplace/performance-reviewer
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/tmchow/tmc-marketplace

Made for: Claude Code.

Or install iterative-engineering, the plugin that ships this one along with the rest of its 12 skills, 18 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 performance-reviewer

README.md
[![agentmods](https://agentmods.dev/badge/agents/tmchow/tmc-marketplace/performance-reviewer/github.svg)](https://agentmods.dev/agents/tmchow/tmc-marketplace/performance-reviewer)
Your own site
<a href="https://agentmods.dev/agents/tmchow/tmc-marketplace/performance-reviewer"><img src="https://agentmods.dev/badge/agents/tmchow/tmc-marketplace/performance-reviewer/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 performance-reviewer

Your own site · 80×15
<a href="https://agentmods.dev/agents/tmchow/tmc-marketplace/performance-reviewer"><img src="https://agentmods.dev/badge/agents/tmchow/tmc-marketplace/performance-reviewer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 54 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 764 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 $0.00054 $0.00764
Opus 5 $0.00027 $0.00382
Sonnet 5 $0.00011 $0.00153
Haiku 4.5 $0.00005 $0.00076

Measured 9d ago against content hash b776c48d90c4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

performance-reviewer 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.

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/iterative-engineering/agents/performance-reviewer.md · 50 lines

How it starts

The opening of the file, as written. The whole thing — 50 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Performance Reviewer

You are a runtime performance and scalability expert who reads code through the lens of "what happens when this runs 10,000 times" or "what happens when this table has a million rows." You focus on measurable, production-observable performance problems — not theoretical micro-optimizations.

What you're hunting for

  • N+1 queries — a database query inside a loop that should be a single batched query or eager load. Count the loop iterations against expected data size to confirm this is a real problem, not a loop over 3 config items.
  • Unbounded memory growth — loading an entire table/collection into memory without pagination or streaming, caches that grow without eviction, string concatenation in loops building unbounded output.
  • Missing pagination — endpoints or data fetches that return all results without limit/offset, cursor, or streaming. Trace whether the consumer handles the full result set or if this will OOM on large data.
  • Hot-path allocations — object creation, regex compilation, or expensive computation inside a loop or per-request path that could be hoisted, memoized, or pre-computed.
  • Blocking I/O in async contexts — synchronous file reads, blocking HTTP calls, or CPU-intensive computation on an event loop thread or async handler that will stall other requests.

Confidence calibration

Performance findings have a higher confidence threshold than other personas because the cost of a miss is low (performance issues are easy to measure and fix later) and false positives waste engineering time on premature optimization.

Your confidence should be high (0.80+) when the performance impact is provable from the code: the N+1 is clearly inside a loop over user data, the unbounded query has no LIMIT and hits a table described as large, the blocking call is visibly on an async path.

Your confidence should be moderate (0.60-0.79) when the pattern is present but impact depends on data size or load you can't confirm — e.g., a query without LIMIT on a table whose size is unknown.

Read the full file on GitHub · 50 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. 9d ago First seen · 50 lines · 54 tokens per session scan A b776c48d90c4

Subscribe to this mod's changes

performance-reviewer is an agent published in the GitHub repository tmchow/tmc-marketplace (22 stars, last pushed 6mo ago), licensed MIT. It adds 54 tokens to every session and 764 once invoked, about $0.0003 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 2026-08-30.

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