performance-optimizer

performance-optimizer is an agent for Claude Code from sd0xdev/sd0x-harness. It costs 22 tokens per session (450 once invoked), scanned A, original, MIT.

An assistant for finding common causes of slow software, such as repeated database queries, memory leaks, blocking work, and missing or poorly managed caches.

In plain words
What is it for?
Inspecting database access, memory handling, concurrent work, and caching, then identifying patterns such as one query per user or sequential waits in large loops.
Why use it?
It helps locate performance bottlenecks that can make applications respond slowly or consume too many resources.

Agent for Claude Code

Written for Claude Code: effort in frontmatter. Also seen: model in frontmatter.

Part of the sd0x-dev-flow plugin — 101 skills, 16 agents, 5 hooks shipped together

Good fit Inspecting database access, memory handling, concurrent work, and caching, then identifying patterns such as one query per user or sequential waits in large loops.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/sd0xdev/sd0x-harness/performance-optimizer
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/sd0xdev/sd0x-harness

Made for: Claude Code.

Or install sd0x-dev-flow, the plugin that ships this one along with the rest of its 101 skills, 16 agents, 5 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 performance-optimizer

README.md
[![agentmods](https://agentmods.dev/badge/agents/sd0xdev/sd0x-harness/performance-optimizer/github.svg)](https://agentmods.dev/agents/sd0xdev/sd0x-harness/performance-optimizer)
Your own site
<a href="https://agentmods.dev/agents/sd0xdev/sd0x-harness/performance-optimizer"><img src="https://agentmods.dev/badge/agents/sd0xdev/sd0x-harness/performance-optimizer/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-optimizer

Your own site · 80×15
<a href="https://agentmods.dev/agents/sd0xdev/sd0x-harness/performance-optimizer"><img src="https://agentmods.dev/badge/agents/sd0xdev/sd0x-harness/performance-optimizer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 22 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 450 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 $0.00022 $0.00450
Opus 5.5 $0.00009 $0.00180
Sonnet 5.5 $0.00004 $0.00090
Haiku 4.5 $0.00002 $0.00045

Measured 1mo ago against content hash 74f7d33c208f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

performance-optimizer 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 1mo 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.

agents/performance-optimizer.md · 85 lines

What it actually says

Performance Optimizer Agent

Expert in identifying and resolving performance bottlenecks

Inspection Dimensions

Dimension Checks
Queries N+1 issues, missing indexes, full table scans
Memory Leaks, large arrays, unreleased resources
Concurrency Blocking operations, lock contention, event loop blocking
Caching Missing cache, cache penetration, expiry strategy

Common Problem Patterns

N+1 Query

// ❌ Bad: N+1
for (const user of users) {
  const orders = await this.orderRepo.findByUserId(user.id);
}

// ✅ Good: Batch query
const userIds = users.map(u => u.id);
const orders = await this.orderRepo.findByUserIds(userIds);

Await in Large Loops

// ❌ Bad: Sequential execution
for (const item of items) {
  await processItem(item);
}

// ✅ Good: Parallel execution
await Promise.all(items.map(item => processItem(item)));

Unreleased Resources

// ❌ Bad: Connection not released
const conn = await pool.getConnection();
const result = await conn.query(sql);
// Forgot conn.release()

// ✅ Good: Use try-finally
const conn = await pool.getConnection();
try {
  return await conn.query(sql);
} finally {
  conn.release();
}

Output Format

## Performance Analysis Report

### Issues Found

| Level | Location  | Issue     | Impact       |
| :---: | :-------- | :-------- | :----------- |
|  P0   | file:line | N+1 query | High latency |

### Optimization Suggestions

1. **Issue description**
   - Location: file:line
   - Current: ...
   - Suggestion: ...
   - Expected improvement: ...
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. 1mo ago First seen · 85 lines · 22 tokens per session scan A 74f7d33c208f

Subscribe to this mod's changes

performance-optimizer is an agent published in the GitHub repository sd0xdev/sd0x-harness (193 stars, last pushed 9d ago), licensed MIT. It adds 22 tokens to every session and 450 once invoked, about $0.0001 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 2026-08-30.