perf-check

perf-check is a skill for Claude Code, Codex from huzaifa525/claude-code-optimizer. It costs 25 tokens per session (446 once invoked), scanned A, original, MIT.

A checklist for reviewing code performance, meaning how efficiently it uses time, memory, and network resources.

In plain words
What is it for?
Auditing databases, backend code, frontend applications, APIs, network requests, memory use, file handling, and algorithms for bottlenecks.
Why use it?
It helps find common causes of slow applications, such as repeated database queries, unnecessary browser updates, oversized responses, and unclosed resources.

Skill for Claude CodeCodex

Part of the claude-code-optimizer plugin — 25 skills, 4 hooks shipped together

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 skills/huzaifa525/claude-code-optimizer/perf-check
Any agent
npx skills add huzaifa525/claude-code-optimizer --skill perf-check
Clone the repo
git clone --depth 1 https://github.com/huzaifa525/claude-code-optimizer

Made for: Claude Code, Codex.

Or install claude-code-optimizer, the plugin that ships this one along with the rest of its 25 skills, 4 hooks.

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 perf-check

README.md
[![agentmods](https://agentmods.dev/badge/skills/huzaifa525/claude-code-optimizer/perf-check.svg)](https://agentmods.dev/skills/huzaifa525/claude-code-optimizer/perf-check)
Your own site
<a href="https://agentmods.dev/skills/huzaifa525/claude-code-optimizer/perf-check"><img src="https://agentmods.dev/badge/skills/huzaifa525/claude-code-optimizer/perf-check.svg" alt="Measured on agentmods" height="20"></a>
Per session 25 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 446 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 $0.00025 $0.00446
Opus 5 $0.00013 $0.00223
Sonnet 5 $0.00005 $0.00089
Haiku 4.5 $0.00003 $0.00045

Measured 4d ago against content hash b9932aa1cfa3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

perf-check 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 4d 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.

templates/.claude/skills/perf-check/SKILL.md · 69 lines

What it actually says

Analyze $ARGUMENTS for performance issues.

Check Categories

Database & Queries

  • N+1 query patterns (loop with query inside)
  • Missing indexes on frequently queried columns
  • SELECT * instead of specific columns
  • Missing pagination on list endpoints
  • Unoptimized joins or subqueries

Memory & Resources

  • Unclosed connections, streams, file handles
  • Growing arrays/maps without limits
  • Event listeners not removed on cleanup
  • Large objects held in memory unnecessarily
  • Missing cleanup in useEffect (React)

Frontend Performance

  • Unnecessary re-renders (missing useMemo, useCallback, React.memo)
  • Large bundle imports (import entire library vs specific module)
  • Images without lazy loading or optimization
  • Missing code splitting
  • Synchronous operations blocking UI thread
  • Missing virtualization for long lists

API & Network

  • Missing caching (Redis, in-memory, HTTP cache headers)
  • Redundant API calls
  • Missing request deduplication
  • Large payloads without compression
  • Missing connection pooling

General

  • O(n²) or worse algorithms where O(n) is possible
  • Synchronous file I/O in async context
  • Regex backtracking (catastrophic regex)
  • Unnecessary deep cloning

Output Format

## Performance Report: [target]

### Critical (fix now)
- [file:line] [issue] [impact] [fix]

### Warning (should fix)
- [file:line] [issue] [impact] [fix]

### Suggestion (optimization)
- [file:line] [issue] [impact] [fix]

### Good Patterns Found
- [what's already well-optimized]
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. 4d ago First seen · 69 lines · 25 tokens per session scan A b9932aa1cfa3

Subscribe to this mod's changes

perf-check is a skill published in the GitHub repository huzaifa525/claude-code-optimizer (9 stars, last pushed 5mo ago), licensed MIT. It adds 25 tokens to every session and 446 once invoked, about $0.0001 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 2026-08-31.