# Third Party Scripts

> Use when auditing slow page loads, heavy assets, or rendering delays related to Optimize third-party script loading. Verify the actual bottleneck in DevTools, Lighthouse, or field data before recommending changes.

- Skill: `thedaviddias/third-party-scripts` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add thedaviddias/third-party-scripts`
- Raw SKILL.md: https://api.skillmd.com/api/skills/thedaviddias/third-party-scripts/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: thedaviddias (https://skillmd.com/u/thedaviddias)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/thedaviddias/third-party-scripts

---


# Optimize third-party script loading

Third-party scripts are the #1 cause of slow websites—unoptimized loading can add 2-5 seconds to your page load time.

## Quick Reference

- Use async for independent scripts (analytics, ads)
- Use defer for DOM-dependent scripts (chat widgets, social)
- Lazy-load non-critical scripts after page load
- Consider self-hosting critical third-party scripts

## Check

Analyze third-party scripts on this page to ensure they use async/defer and don't block rendering.

## Fix

Add async or defer attributes to third-party scripts and consider lazy loading non-critical scripts.

## Explain

Explain the performance impact of third-party scripts and strategies to minimize their blocking effect.

## Code Review

Review the routes, assets, and loading behavior that affect Optimize third-party script loading. Flag exact files, requests, or rendering steps that add unnecessary network, CPU, or layout cost, and describe the measurement method used to confirm the issue.

---

For full implementation details, code examples, and framework-specific guidance,
see `references/rule.md`.

Rule page: https://frontendchecklist.io/en/rules/performance/third-party-scripts