Jetpack Boost

Jetpack Boost helps your site load faster by optimizing how key assets are delivered—like CSS, JavaScript, and images. This guide explains how to install Boost, what each feature does, and how to use them.

You can get started for free, or upgrade to unlock premium features like automatic CSS optimization, image quality controls, and advanced image analysis.

WordPress.com hosting plans (Business or Commerce) don’t include premium Jetpack Boost features—you’ll need a Paid Boost plan to use them. See Using Jetpack Boost on WordPress.com below for activation steps.

Installation Requirements MD

To use Jetpack Boost, make sure your site:

• Runs the latest version of WordPress.
• Is publicly accessible (not behind a password or maintenance mode).
• Meets WordPress hosting requirements.
• Has a publicly accessible xmlrpc.php file.

You don’t need the Jetpack plugin to use Boost. Jetpack Boost is a separate plugin.

Install Jetpack BoostMD

1. From WP Admin → Plugins → Add New, search for Jetpack Boost.
2. Click Install Now, then Activate.
3. Choose a Free or Paid plan.
4. After activation, you’ll be redirected to the Boost dashboard, where Boost calculates your Overall, Desktop, and Mobile performance scores.

If Jetpack Boost can’t connect to your site, follow these troubleshooting steps.

Jetpack Boost DashboardMD

Once installed, the Boost dashboard shows your site’s Overall, Desktop, and Mobile performance scores under Your site speed.

Score gain badges may appear below the Desktop and Mobile scores to show how optimizations affected your performance.

Use the Run speed test button in the top-right corner of the Boost screen to update your scores after making changes.

Boost groups optimization settings under Optimize your speed in collapsible sections for Cornerstone Pages, page loading, code optimization, and images. Performance history is available on paid plans.

Activity LogMD

Jetpack Boost 4.7.0 and later add an Activity Log page to WP Admin. The Activity Log (also called site activity) records what happens on your site, including published and updated posts and pages, comment moderation, plugin and theme changes, settings changes, and login attempts.

To view it, go to Jetpack → Activity Log in WP Admin.

The Activity Log page requires all of the following:

• Jetpack Boost 4.7.0 or later.
• A site connected to WordPress.com, with your user account linked to that connection.
• The Administrator role on the site.

You do not need the Jetpack plugin. Boost provides the Activity Log page on its own.

With the free version of Boost, the Activity Log shows the 20 most recent events and filtering is unavailable. A paid Jetpack VaultPress Backup, Jetpack Security, or Jetpack Complete plan extends the event history and unlocks filtering by date range and activity type. The Activity Log cannot be exported to a file.

Feature ReferenceMD

Jetpack Boost includes tools to help improve and monitor your site’s front-end performance. You can manage optimization features from the Optimize your speed section of the Boost dashboard.

Feature	Free	Paid
Site Performance Scores View site performance scores based on Google PageSpeed Insights. Learn more.	✅	✅
Performance History Track your performance history over time.	❌	✅
Cornerstone Pages Prioritizes your most important pages for targeted optimizations, including Critical CSS and LCP image optimization.	One (1) page	Ten (10) pages
Optimize CSS Loading Generates Critical CSS to prioritize the styles needed to display the visible part of your page.	✅	✅
Automated Critical CSS Optimizes CSS loading automatically after changes.	❌	✅
Cache Site Pages Creates static versions of your pages to reduce load time for visitors.	✅	✅
Defer non‑essential JavaScript Delays the loading of scripts that aren’t required for initial rendering, helping your content appear faster	✅	✅
Concatenate JavaScript and CSS Combines multiple JavaScript or CSS files into one to improve load performance.	✅	✅
Image CDN Delivers your images from Jetpack’s high-speed global CDN.	✅	✅
Adjust image quality per format Adds image quality controls to CDN-served images and access to lazy load resizing.	❌	✅
Enable image guide Shows image size information as you browse, helping you spot images that may be too large. Learn more.	✅	✅

Cornerstone PagesMD

Cornerstone Pages help Boost prioritize performance improvements on your most important content. Boost focuses on these pages when generating Critical CSS and Page Speed scores. Your homepage will always be considered a Cornerstone Page.

• On the Free plan, you can set one additional Cornerstone Page.
• On the Paid plan, you can set up to ten additional pages.

By default, Boost adds:

• Your WooCommerce shop page (if active).
• Pages marked as Cornerstone Content in the Yoast SEO plugin.

Note: If you’re on a Free plan, only one page from the above (not counting home page) will be added when you first install Jetpack Boost.

You can view or change this list from the Cornerstone Pages section under Optimize your speed in the Boost dashboard.

Boost stores Cornerstone Pages as relative URLs, so if you change domains, your list will continue working without updating anything.

Cornerstone Pages affect:

• Speed scores: Boost uses the first page in the list to measure performance.
• Critical CSS: Each Cornerstone Page gets its own optimized CSS, improving loading precision.

Prerender Cornerstone Pages

When enabled, this feature uses WordPress 6.8’s speculative loading to prerender Cornerstone Pages in supported browsers. This means linked pages may begin loading in the background when users hover over them, resulting in faster perceived performance when they click.

You can toggle this on or off from the Cornerstone Pages section in the Boost dashboard. It’s off by default.

Learn more about Cornerstone Pages.

Optimize CSS LoadingMD

Optimize CSS Loading generates Critical CSS, the styles needed to display the visible part of your page, and loads those styles first so content can render faster.

• On the Free plan, select the Generate button the first time you use the feature. When Critical CSS needs to be updated later, select the “Regenerate Critical CSS” button.
• On the Paid plan, Boost generates and updates Critical CSS automatically.

If Site Health reports “Outdated Critical CSS,” follow the link to the Boost dashboard and select the “Regenerate Critical CSS” button.

Stay on the Boost dashboard while Critical CSS is being generated. If you navigate away, the process will pause.

Learn more about optimizing CSS.

Optimize LCP Images (Free for 1 page, Paid for up to 10)MD

Optimizes the Largest Contentful Paint (LCP) image on your Cornerstone Pages to improve perceived load time and Core Web Vitals scores.

Free plan: Optimizes one Cornerstone Page.
Paid plan: Optimizes up to ten.

Automatically identifies the largest visible image or background image and:

• Prioritizes loading with fetchpriority="high"
• Disables lazy loading for LCP images
• Uses Jetpack CDN and responsive image techniques
• Preloads background images with image-set()

Learn more about LCP Image Optimization

Cache Site PagesMD

Cache Site Pages creates static versions of your pages to reduce load time for visitors.

• Boost automatically updates the cache when your content changes.
• You can exclude specific pages from caching, which can be useful for frequently updated content.

To enable page caching:

1. Expand the “Page loading” section.
2. Turn on the “Cache Site Pages” toggle.
3. To exclude pages from caching, open the Except panel and add the URL patterns you want to exclude.

On WP Cloud hosts, including Pressable and WordPress.com, Boost can detect the hosting provider’s page cache. In this case, Boost shows Page Cache is running instead of the “Cache Site Pages” toggle, and no additional page cache setup is needed.

Learn more about caching site pages with Boost.

Defer Non-Essential JavaScriptMD

Defer Non-Essential JavaScript delays scripts that aren’t required for initial rendering, helping your content appear faster.

To enable it, expand the “Page loading” section and turn on the “Defer Non-Essential JavaScript” toggle.

If site features break, such as forms or sliders, they may depend on JavaScript that needs to load earlier. You can:

• Turn off the “Defer Non-Essential JavaScript” toggle.
• Open the Except panel and add the URLs or URL patterns where JavaScript should not be deferred.
• To exclude a specific script instead, add data-jetpack-boost="ignore" to its script tag.

Concatenate JavaScriptMD

Concatenate JavaScript combines and minifies JavaScript files to reduce the number of scripts your site needs to load.

To enable it, expand the “Code optimization” section and turn on the “Concatenate JavaScript” toggle.

Excluding specific scripts

Some JavaScript files may not function correctly when combined. To exclude them you can identify the script’s handle by checking your page’s source code or plugin documentation.

 Example script tag:

https://yourjetpack.blog/wp-content/plugins/snow-effects/snow-effects.js

1.  The handle is: snow-effects.
   
2. Open the Except panel, add snow-effects to the list of handles, and select the Save button.
   

When successful, you’ll see a comment like this in the page source:

<!-- No Concat JS snow-effects => Excluded option -->

This feature works only with scripts added via the WordPress Enqueue API. It doesn’t affect inline or embedded scripts.

Concatenate CSSMD

Concatenate CSS combines and minifies stylesheet files to reduce the number of styles your site needs to load.

To enable it, expand the “Code optimization” section and turn on the “Concatenate CSS” toggle.

Excluding specific stylesheets

Some stylesheets may break when combined. To exclude them, you can find the stylesheet’s handle from the id attribute in the HTML.

 Example:

<link rel="stylesheet" href="https://yourjetpack.blog/wp-content/themes/twentytwenty/style.css" id="twentytwenty-style-css">

1.  The handle is: twentytwenty-style.
   
2. Open the Except panel, add twentytwenty-style to the list of handles, and select the Save button.

Like JS concatenation, this works only with styles added using the WordPress Enqueue API.

Image CDNMD

Delivers your images from Jetpack’s high-speed global CDN. This also converts images to more efficient formats like WebP for faster loading.

To enable it, expand the “Images” section and turn on the “Image CDN” toggle.

• Free plan: Images are optimized and served via the CDN automatically.
• Paid plan: Adds image quality controls and access to lazy load resizing.

Adjust image quality per format (Paid feature)

With a Paid Boost plan, expand Adjust image quality per format under Image CDN to control the quality of JPEG, PNG, and WebP images.

Adjust the quality level for each format with the slider, or select the Lossless checkbox to preserve image quality without lossy compression.

Auto-Resize Lazy Images (Paid feature)

Resizes lazily loaded images so they better match the size of their container. This helps reduce layout shifts and improves Cumulative Layout Shift (CLS).

• Auto-Resize Lazy Images is available with a Paid Boost plan when Image CDN is enabled.
• Turn on the “Auto-Resize Lazy Images” toggle to resize lazy-loaded images to match their displayed dimensions.

Enable Image GuideMD

The image guide shows image size information as you browse your site, helping you spot images that may be too large.

To use it, expand the “Images” section and turn on the “Enable image guide” toggle.

This is especially useful if you’re unsure where to begin with image optimization.

Multisite and Local UsageMD

• Multisite installations: Log page is not available on multisite networks and does not appear on any site in a network.
• Local environments: Use Offline Mode to test Boost on private or local sites.

Jetpack Boost Troubleshooting HubMD

If Jetpack Boost isn’t working as expected, we have helpful documentation to get things back on track. Most issues can be fixed with a few simple steps—starting with the right diagnosis.

Use the guide below to find common issues, organized by feature. Each link opens a dedicated troubleshooting article with detailed instructions.

Caching	Fix problems with Boost’s page caching—like file access issues or conflicts with other plugins.	Troubleshooting Jetpack Boost caching issues
Critical CSS	Solve errors related to outdated or missing Critical CSS.	Troubleshooting Critical CSS in Jetpack Boost
Concatenate CSS/JS	Fix layout or script errors caused by CSS or JavaScript concatenation.	Troubleshooting Concatenated CSS or JavaScript Delivery Methods
JavaScript Deferral	Learn how to exclude scripts that break when loaded late.	Exclude JavaScript files from Jetpack Boost deferral
Speed Score Measurement	Understand how Boost calculates speed scores and what each metric means.	How the speed score is measured with Jetpack Boost
Console Errors	Troubleshoot JavaScript or CSS errors reported in your browser’s console.	Understand Console Errors in Jetpack Boost
Cache Filter Customization	For developers: customize how Boost handles caching using optional filters and config files.	Using Filters to Customize Cache Parameters in Jetpack Boost
Speed Score Fluctuations	Understand why your Boost may change with each speed test, and how to test more reliably.	Why my Jetpack Boost speed score changes (and what to do about it)
LCP Image Optimization	Fix issues preventing Boost from optimizing your Largest Contentful Paint images.	Troubleshooting common issues with Optimize LCP Images within Jetpack Boost

Need help?MD

If you’re having trouble setting up or using Jetpack Boost, contact Jetpack Support. We’re happy to help.

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Privacy InformationMD

We are fully committed to the privacy and security of our customers and their personal data. For a better understanding of how Jetpack Boost uses your data, please refer to the Automattic Privacy Notice (Automattic owns and operates the Jetpack Boost plugin), the Automattic Privacy Policy, and the following section.

Jetpack Boost uses Jetpack libraries to connect to WordPress.com and calculate the page speed score (making use of the tk_ai cookie). There is more information about cookies within Jetpack here.