What is performance-optimization?

A guide for finding and fixing Rails performance problems, including N+1 queries, slow database queries, and excessive memory use. An N+1 query happens when code makes one query for a list and then another query for each item.

Detecting N+1 queries, improving database queries, choosing eager-loading methods, adding indexes or counter caches, profiling requests and memory, and writing query-count tests.

It helps locate unnecessary database work and resource use that can make pages and requests slow. It provides patterns for loading related records efficiently and measuring improvements.

performance-optimization — Skill for Claude Code by ThibautBaissac

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.

Any agent

npx skills add ThibautBaissac/rails_ai_agents --skill performance-optimization

Clone the repo

git clone --depth 1 https://github.com/ThibautBaissac/rails_ai_agents

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/thibautbaissac/rails_ai_agents/performance-optimization/github.svg)](https://agentmods.dev/skills/thibautbaissac/rails_ai_agents/performance-optimization)

Your own site

<a href="https://agentmods.dev/skills/thibautbaissac/rails_ai_agents/performance-optimization"><img src="https://agentmods.dev/badge/skills/thibautbaissac/rails_ai_agents/performance-optimization/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/thibautbaissac/rails_ai_agents/performance-optimization"><img src="https://agentmods.dev/badge/skills/thibautbaissac/rails_ai_agents/performance-optimization.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 80 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,111 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. Third-party audits

NVIDIA SkillSpector pass 7 Sept 2026

How audits are shown

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.

Model	Per session	Once invoked
Fable 5.1	$0.00080	$0.01111
Opus 5.5	$0.00032	$0.00444
Sonnet 5.5	$0.00016	$0.00222
Haiku 4.5	$0.00008	$0.00111

Measured 2mo ago against content hash 235c8cbfabae, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

performance-optimization 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 2mo 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/skills/performance-optimization/SKILL.md · 122 lines

How it starts

The opening of the file, as written. The whole thing — 122 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Performance Optimization for Rails 8

Overview

Performance optimization focuses on:

N+1 query detection and prevention
Query optimization
Memory management
Response time improvements
Database indexing

Quick Start

# Gemfile
group :development, :test do
  gem 'bullet'           # N+1 detection
  gem 'rack-mini-profiler' # Request profiling
  gem 'memory_profiler'  # Memory analysis
end

N+1 Query Detection and Prevention

N+1 queries occur when code loads a collection then makes a separate query for each associated record. The Bullet gem detects these automatically. Fix them with eager loading via includes, preload, or eager_load.

Eager Loading Decision Table

Method	Use When
`includes`	Most cases (Rails chooses best strategy)
`preload`	Forcing separate queries, large datasets
`eager_load`	Filtering on association, need single query
`joins`	Only need to filter, don't need association data

Key patterns: Bullet configuration, eager loading methods, scoped eager loading, counter caches, N+1 specs with query count assertions.

See references/n-plus-one.md for all code examples and patterns.

Query Optimization

Optimize queries by selecting only needed columns, using batch processing for large datasets, and choosing efficient existence checks.

Key Patterns

Pattern	Bad	Good
Column selection	`User.all.map(&:name)`	`User.pluck(:name)`
Large iterations	`Event.all.each { ... }`	`Event.find_each { ... }`
Existence checks	`.any?` / `.present?`	`.exists?`
Collection size	`.length` (loads all)	`.size` (smart)

Database Indexing

Add indexes for: foreign keys, columns in WHERE/ORDER BY/JOIN clauses, and unique constraints. Use composite indexes for multi-column queries. Use partial indexes for filtered subsets.

Query Analysis

Use Event.where(...).explain(:analyze) to inspect query plans. Set up slow query logging via ActiveSupport::Notifications to catch queries over a threshold.

Read the full file on GitHub · 122 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

2mo ago First seen · 122 lines · 80 tokens per session scan A 235c8cbfabae

Subscribe to this mod's changes

performance-optimization is a skill published in the GitHub repository ThibautBaissac/rails_ai_agents (672 stars, last pushed 5mo ago), licensed MIT. It adds 80 tokens to every session and 1,111 once invoked, about $0.0003 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.

Backend and APIs Debugging

performance-optimization next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
performance-optimizationThibautBaissac/rails_ai_agents	Skill	672	5mo ago	MIT	A	80	Claude Code
api-integration-architectsickn33/agentic-awesome-skills	Skill	49k	yesterday	MIT	A	33	Claude Code
printing-press-amendmvanhorn/cli-printing-press	Skill	4.9k	yesterday	MIT	A	222	Claude Code
convex-performance-auditopenclaw/clawhub	Skill	9.5k	yesterday	MIT	A	38	Codex
convex-insightsopenclaw/clawhub	Skill	9.5k	yesterday	MIT	A	45	Claude Code, Codex
axiom-networkingCharlesWiltgen/Axiom	Skill	1.3k	yesterday	MIT	A	37	Claude Code
platform-apex-anonymous-runforcedotcom/sf-skills	Skill	1.1k	2d ago	Apache-2.0	A	119	Claude Code