Performance Optimization

Reviewed 2026-10-15codingPrompt / Rule# performance # core-web-vitals # profiling # optimization # frontend

Community skill that gives an agent a measure-first workflow for slow apps: baseline, find the bottleneck, fix one anti-pattern, re-measure, and guard with a budget.

Security Reviewed

One Markdown guide with measure-first workflow and examples; nothing to run, no network, no keys.

Install Performance Optimization in Google Antigravity

Antigravity loads skills from .agents/skills/ in your project or ~/.gemini/config/skills/ for all projects (official docs). Full guide

EasiestOption 1: paste this to your Antigravity agent

Install the "Performance Optimization" skill for Google Antigravity.
Follow the steps at https://www.antigravityskills.org/install/performance-optimization.md (source: https://github.com/sickn33/antigravity-awesome-skills/tree/main/skills/performance-optimization).
Before running anything, show me what you will download and whether it includes scripts, and wait for my OK.
Install it into this project (.agents/skills/) unless I say global. When done, check that Antigravity lists it as an installed skill.

The agent reads the install file, shows you what it will download and waits for your OK.

Option 2: install it yourself

1. Download the repository
```
git clone --depth 1 https://github.com/sickn33/antigravity-awesome-skills.git /tmp/ag-skills && git -C /tmp/ag-skills log -1 --format=%h
```
We reviewed commit a307264. If the second command prints a different hash, the skill may have changed since our review.
2. Copy the skill into this project (workspace skill)
```
mkdir -p .agents/skills && cp -r /tmp/ag-skills/skills/performance-optimization .agents/skills/
```
Run from your project root. Antigravity reads workspace skills from .agents/skills/<folder>/; this folder holds just SKILL.md (1 file, no scripts).
3. Or install it for all projects (global skill)
```
mkdir -p ~/.gemini/config/skills && cp -r /tmp/ag-skills/skills/performance-optimization ~/.gemini/config/skills/
```
Use this instead of the previous step. Copy only the skills you need: the repo README warns that a large watched skills folder can overload Antigravity's context.
4. Check that Antigravity sees it
Antigravity app: start a new conversation and ask "What skills do you have?"; performance-optimization should be listed. Antigravity CLI: run /skills (/skills reload in a session that was already open).

The repository's own installer (npx agentic-awesome-skills --antigravity --skills <ids> --dry-run, README) can also install selected skills; the copy steps above use the standard Antigravity skill folders and install only this one.

Using Claude Code, Cursor or Codex? See other assistants below.

What is Performance Optimization?

performance-optimization is a community-contributed skill in sickn33's antigravity-awesome-skills collection, and its frontmatter names addyosmani/agent-skills as the declared source. It is a single SKILL.md of guidance, no scripts: a five-step loop (measure, identify, fix, verify, guard), a decision tree for where to start measuring, six anti-pattern fixes with before/after code, a performance budget and a verification checklist. The stance is that you profile first and optimize only what the numbers prove matters.

How to use Performance Optimization?

Install the skill, then describe the symptom (slow first load, laggy interaction, slow endpoint). The agent should pick the matching branch of the "What is slow?" tree, ask you to take a baseline measurement (Lighthouse, DevTools, query log), fix the one bottleneck it finds, and ask you to measure again before calling it done.

Key features of Performance Optimization

✓We counted at a307264: the folder has 1 file, SKILL.md (371 lines, 13,127 bytes), and no scripts
✓We counted: Core Web Vitals targets are a 3-row table - LCP at 2.5 s or less, INP at 200 ms or less, CLS at 0.1 or less count as Good (values as printed in the skill; we did not check them against Google's pages)
✓We counted: Step 3 shows 6 anti-patterns with code - N+1 queries, unbounded data fetching, missing image optimization, unnecessary React re-renders, large bundles and missing caching
✓We counted: the performance budget lists 7 numbers (for example JavaScript under 200 KB gzipped, API p95 under 200 ms, Lighthouse score 90 or more) and shows npx bundlesize and npx lhci autorun as CI checks; these are the skill's suggested defaults, not a standard
✓We counted: the closing Verification checklist has 7 items, the Red Flags list 7 and the Common Rationalizations table 5 ("We'll optimize later", "It's fast on my machine", ...)
✓The skill points to references/performance-checklist.md but this catalog copy does not include that file; a notice at the top of SKILL.md says to get it from the upstream repository and not to claim steps from it were followed

When to use Performance Optimization

1Finding out why a page's LCP or INP is poor before changing any code
2Reviewing a data-fetching change for N+1 queries and missing pagination
3Setting a performance budget and a CI check so a regression gets caught

Source and files

Repository: sickn33/antigravity-awesome-skills (MIT)
Original author source: addyosmani/agent-skills/tree/main/skills/performance-optimization
Upstream risk label: critical
Added upstream: 2026-07-01
SKILL.md size: 12.0 KB
Files in the skill folder: SKILL.md
Listing synced: 2026-10-05 from commit bdacd76

Installation & Setup Guide

Agent Rules / Prompt Setup

Follow these steps (taken from the project's own docs) to configure Performance Optimization in your development environment.

Step 1: Claude Code (manual copy)claude

mkdir -p .claude/skills && cp -r /tmp/ag-skills/skills/performance-optimization .claude/skills/

Not documented per skill by the repository; this uses Claude Code's standard .claude/skills/ folder after the clone above.

Step 2: Cursor: not documented by the projectcursor

The README lists installer targets for several hosts, but gives no per-skill Cursor path, so we do not list one.

Usage Example & Verification

Prompt / Request Example

1) SKILL.md workflow: the agent follows MEASURE -> IDENTIFY -> FIX -> VERIFY -> GUARD and uses the "What is slow?" tree to decide what to measure first.

2) Our example: "Use the performance-optimization skill. Our product list page feels slow on mobile. Tell me what to measure first and what each result would mean before you change any code."
-> The agent should start from the "First page load" branch (bundle size, TTFB, render-blocking resources) and ask for a Lighthouse or DevTools baseline rather than guessing.

3) Our example: "Check this endpoint for N+1 queries and unbounded fetching, and show the before and after query code."
-> The agent compares your code with the skill's two backend anti-patterns (include/join instead of a query per row, take/skip pagination instead of loading all rows).

Security Review

Static review

Reviewed Date

2026-10-15

Audited Ref / Commit

a3072641b750a1fb2f6ce695a5f984ea3d4c3ec1

Reviewer

antigravityskills.org (static review)

One Markdown guide with measure-first workflow and examples; nothing to run, no network, no keys.

Full review: scope, findings, risks

Audit Scope:SKILL.md read in full; repository README install and disclaimer sections and LICENSE, all at commit a307264 (2026-10-15). The referenced references/performance-checklist.md is not in the folder and was not read. Static review only; nothing was executed.

Key Findings:Instruction-only skill. One Markdown file; the code blocks are TypeScript, React, HTML and shell examples shown as advice. No executable files, no commands the skill runs itself, no URLs fetched by the skill, no credentials needed.

Identified Operational Risks & Permissions:Low. The agent may edit your code if you ask it to apply a fix, and the skill suggests installing and running npx bundlesize and npx lhci in CI; check those before adding them. Advice quality depends on real measurements.

The single SKILL.md was read for commands, URLs, file operations and credential handling. The code blocks are examples (N+1 query fix, pagination, responsive images, React memoization, lazy imports, caching headers). The two shell commands in the budget section (npx bundlesize, npx lhci autorun) are shown as CI examples for you to adopt; the skill does not run them itself. This is a read of the text, not a behaviour test.

Operational Notes & Known Limitations

Known Limitations

•It is generic advice with TypeScript, React and Prisma-style examples; it does not run a profiler or Lighthouse for you, you or the agent must run them and report the numbers
•The thresholds and budget numbers are rules of thumb; set your own from your product's data
•The referenced performance-checklist.md is not in this folder, so the extra checklist it promises is unavailable here
•The skill's own Limitations section says examples are not a substitute for environment-specific tests, security review or approval for costly actions

Frequently Asked Questions

Is the Performance Optimization skill safe?

It is one Markdown file. We read all of it and found no scripts, no commands the skill runs by itself, no network calls beyond tools you choose to use (Lighthouse, DevTools, npx bundlesize, npx lhci) and no API keys. Its frontmatter labels it risk: critical, a generic label in this collection, so read what the agent proposes before you apply code changes.

How do I install Performance Optimization in Antigravity?

Clone sickn33/antigravity-awesome-skills, copy skills/performance-optimization into .agents/skills/ (or ~/.gemini/config/skills/), then ask "What skills do you have?" (Antigravity CLI: /skills).

Does it measure my site for me?

No. It tells the agent to measure first and shows what to look at, but the measurements come from tools such as Lighthouse, DevTools or your database log.

Where is performance-checklist.md?

The SKILL.md refers to references/performance-checklist.md, which is not part of this catalog copy. Its notice says to take it from the upstream repository, addyosmani/agent-skills, if you need it.

Is it an official Google skill?

No. It is community-contributed to an independent collection whose README says it is not affiliated with or endorsed by Google.

Supported Platforms

antigravityclaude

View Source on GitHub

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