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Page Speed Checklist

A comprehensive checklist to improve your core web vitals.

About the Page Speed Checklist

The Page Speed Checklist is an interactive, comprehensive guide for front-end developers aiming to achieve 100/100 performance scores. While automated tools are useful, a manual audit ensures you address the foundational architecture of your site rather than just treating the symptoms.

Features

  • Structured Audit: Categories are broken down logically into Images, Web Fonts, JS/CSS, Caching, and Server configurations so you can tackle optimization methodically.
  • Persistent State: Your progress is saved automatically to your local browser storage. You can safely close the tab and return later to continue your audit.
  • Actionable Insights: Each checklist item includes a brief explanation of *why* it matters, and provides links out to official documentation (like MDN or web.dev) for deeper learning.
  • Export to Markdown: Once you've completed your audit, click 'Copy as Markdown' to generate a formatted list. This is perfect for pasting into GitHub Issues, Pull Requests, or internal documentation.

Start from the top and work your way down. Even implementing half of these recommendations will drastically improve your Time to First Byte (TTFB) and Largest Contentful Paint (LCP).

Frequently Asked Questions

What affects website page speed the most?

The biggest culprits of slow page speed are typically massive unoptimized images, render-blocking JavaScript or CSS, lacking a Content Delivery Network (CDN), and slow server response times (TTFB).

What is Core Web Vitals?

Core Web Vitals are a set of specific metrics created by Google to measure user experience. They focus primarily on loading performance (LCP), interactivity (INP/FID), and visual stability (CLS) of a webpage.

How do I improve LCP (Largest Contentful Paint)?

To improve LCP, you must optimize your critical rendering path. This involves compressing your hero images, utilizing modern formats like WebP or AVIF, and ensuring critical CSS is inlined so the largest element renders immediately.

Does page speed affect SEO ranking?

Yes. Google has officially confirmed that page speed is a direct ranking factor for both mobile and desktop searches. Faster websites provide better user experiences, leading to lower bounce rates and higher conversions.

What causes layout shift (CLS) on a website?

Cumulative Layout Shift (CLS) is usually caused by images or embedded elements loading without explicit width and height dimensions defined in the HTML. It can also be caused by web fonts loading late and swapping sizes, or ads injecting themselves dynamically into the content.