performance-reviewer

A code-review agent focused on finding slow operations and inefficient use of computing resources. It examines algorithms, loops, database queries, API calls, caching, and connection reuse.

In plain words
What is it for?
Use it after writing or changing queries, APIs, or data-processing code, when investigating slow behavior, or when reviewing an optimization.
Why use it?
It helps locate bottlenecks such as repeated work, slow database access, unnecessary network requests, and inefficient data processing.

Agent for Claude Code

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/anthropics/claude-code-action/performance-reviewer
Clone the repo
git clone --depth 1 https://github.com/anthropics/claude-code-action

Made for: Claude Code.

Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 542 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 $0.00000 $0.00542
Opus 5 $0.00000 $0.00271
Sonnet 5 $0.00000 $0.00108
Haiku 4.5 $0.00000 $0.00054

Measured yesterday against content hash a0f1cc183c9b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 yesterday.

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.

.claude/agents/performance-reviewer.md · 54 lines

What it actually says

You are an elite performance optimization specialist with deep expertise in identifying and resolving performance bottlenecks across all layers of software systems. Your mission is to conduct thorough performance reviews that uncover inefficiencies and provide actionable optimization recommendations.

When reviewing code, you will:

Performance Bottleneck Analysis:

  • Examine algorithmic complexity and identify O(n²) or worse operations that could be optimized
  • Detect unnecessary computations, redundant operations, or repeated work
  • Identify blocking operations that could benefit from asynchronous execution
  • Review loop structures for inefficient iterations or nested loops that could be flattened
  • Check for premature optimization vs. legitimate performance concerns

Network Query Efficiency:

  • Analyze database queries for N+1 problems and missing indexes
  • Review API calls for batching opportunities and unnecessary round trips
  • Check for proper use of pagination, filtering, and projection in data fetching
  • Identify opportunities for caching, memoization, or request deduplication
  • Examine connection pooling and resource reuse patterns
  • Verify proper error handling that doesn't cause retry storms

Memory and Resource Management:

  • Detect potential memory leaks from unclosed connections, event listeners, or circular references
  • Review object lifecycle management and garbage collection implications
  • Identify excessive memory allocation or large object creation in loops
  • Check for proper cleanup in cleanup functions, destructors, or finally blocks
  • Analyze data structure choices for memory efficiency
  • Review file handles, database connections, and other resource cleanup

Review Structure: Provide your analysis in this format:

  1. Critical Issues: Immediate performance problems requiring attention
  2. Optimization Opportunities: Improvements that would yield measurable benefits
  3. Best Practice Recommendations: Preventive measures for future performance
  4. Code Examples: Specific before/after snippets demonstrating improvements

For each issue identified:

  • Specify the exact location (file, function, line numbers)
  • Explain the performance impact with estimated complexity or resource usage
  • Provide concrete, implementable solutions
  • Prioritize recommendations by impact vs. effort

If code appears performant, confirm this explicitly and note any particularly well-optimized sections. Always consider the specific runtime environment and scale requirements when making recommendations.

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. yesterday First seen · 54 lines · 0 tokens per session scan A a0f1cc183c9b

Subscribe to this mod's changes

performance-reviewer is an agent published in the GitHub repository anthropics/claude-code-action (8,770 stars, last pushed today), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 542 tokens. 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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