How to Fix Core Web Vitals and Speed Up a Slow WordPress Site

Introduction to Core Web Vitals

Core Web Vitals are a set of metrics that measure the performance and user experience of a website. They include Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), and Instantaneous Input Delay (INP). In this guide, we will walk through the steps to measure and improve these metrics using various tools and techniques.

Measuring Core Web Vitals with PageSpeed

To measure Core Web Vitals, we can use Google PageSpeed Insights. This tool provides a detailed report on the performance of a website, including LCP, CLS, and INP.

1. Open PageSpeed Insights and enter the URL of the website.
2. Click on the "Analyze" button to generate a report.
3. Look for the "Core Web Vitals" section in the report, which provides the metrics for LCP, CLS, and INP.

Caching

Caching is a technique that stores frequently-used resources in memory or on disk, reducing the need to reload them from the server. This can significantly improve the performance of a website.

Enabling Caching

To enable caching, we can use the following steps:

1. Install a caching plugin, such as W3 Total Cache or WP Super Cache, if using WordPress.
2. Configure the caching settings to cache pages, posts, and other resources.
3. Set the cache expiration time to a reasonable value, such as 1 hour or 1 day.

Verifying Caching

To verify that caching is working, we can use the following command:

curl -I https://example.com

Look for the "Cache-Control" header in the response, which should indicate that the resource is cached.

Image and AVIF Optimization

Optimizing images can significantly reduce the page load time. We can use tools like ImageOptim or ShortPixel to compress images.

Converting Images to AVIF

AVIF is a new image format that provides better compression than JPEG or PNG. We can use the following command to convert an image to AVIF:

ffmpeg -i input.jpg output.avif

Verifying Image Optimization

To verify that images are optimized, we can use the following command:

imageoptim --check https://example.com/image.jpg

This will report on the optimization status of the image.

Defer JavaScript

Defer JavaScript can improve the page load time by loading non-essential scripts after the initial page load.

Defer JavaScript using HTML

We can defer JavaScript using the "defer" attribute in the HTML script tag:

<script defer src="script.js"></script>

Defer JavaScript using WordPress

If using WordPress, we can use a plugin like WP Rocket to defer JavaScript.

Critical CSS

Critical CSS is the CSS that is required to render the above-the-fold content. We can use tools like CriticalCSS to extract the critical CSS.

Extracting Critical CSS

To extract the critical CSS, we can use the following command:

criticalcss --url https://example.com --output critical.css

Inlining Critical CSS

We can inline the critical CSS in the HTML header using the following code:

<style>
/* critical CSS */
</style>

Reduce TTFB

Time to First Byte (TTFB) is the time it takes for the server to respond to a request. We can reduce TTFB by optimizing the server configuration and database.

Optimizing Server Configuration

To optimize the server configuration, we can use the following steps:

1. Enable HTTP/2 or HTTP/3 to reduce the overhead of multiple requests.
2. Enable Keep-Alive to reduce the overhead of establishing new connections.
3. Configure the server to use a faster PHP version, such as PHP 7.4 or later.

Database Cleanup

To clean up the database, we can use the following steps:

1. Remove unused tables and data.
2. Optimize database queries to reduce the load on the server.
3. Use a database caching mechanism, such as Redis or Memcached.

Using a CDN

A Content Delivery Network (CDN) can reduce the load time by serving resources from a location closer to the user.

Configuring a CDN

To configure a CDN, we can use the following steps:

1. Sign up for a CDN service, such as Cloudflare or MaxCDN.
2. Configure the CDN to serve resources from our website.
3. Update the DNS settings to point to the CDN.

Checklist

Here is a checklist of the steps to improve Core Web Vitals:

• Measure LCP, CLS, and INP using PageSpeed Insights
• Enable caching
• Optimize images and convert to AVIF
• Defer JavaScript
• Extract and inline critical CSS
• Reduce TTFB by optimizing server configuration and database
• Use a CDN

Common Mistakes

Here are some common mistakes to avoid:

• Not measuring Core Web Vitals regularly
• Not optimizing images and videos
• Not deferring non-essential scripts
• Not using a CDN
• Not optimizing server configuration and database

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Originally posted at https://guardlabs.online/care/