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Fast and optimized pages lead to higher visitor engagement, retention, and conversions. The PageSpeed family of tools is designed to help you optimize the performance of your website. PageSpeed Insights products will help you identify performance best practices that can be applied to your site, and PageSpeed optimization tools can help you automate the process.
Page Speed Insights measures the performance of a page for mobile devices and desktop devices. It fetches the url twice, once with a mobile user-agent, and once with a desktop-user agent.
The PageSpeed Score ranges from 0 to 100 points. A higher score is better and a score of 85 or above indicates that the page is performing well. Please note that PageSpeed Insights is being continually improved and so the score will change as we add new rules or improve our analysis.
PageSpeed Insights measures how the page can improve its performance on:
- time to above-the-fold load: Elapsed time from the moment a user requests a new page and to the moment the above-the-fold content is rendered by the browser.
- time to full page load: Elapsed time from the moment a user requests a new page to the moment the page is fully rendered by the browser.
However, since the performance of a network connection varies considerably, PageSpeed Insights only considers the network-independent aspects of page performance: the server configuration, the HTML structure of a page, and its use of external resources such as images, JavaScript, and CSS. Implementing the suggestions should improve the relative performance of the page. However, the absolute performance of the page will still be dependent upon a user’s network connection.
Each suggestion is rated with a priority indicator to indicate its importance:
| Icon | Name | Description |
|---|---|---|
 | red exclamation point | Fixing this would have a measurable impact on page performance. |
 | yellow exclamation point | Consider fixing this if it is not a lot of work. |
 | green check mark | No significant issues found. Good job! |
The most recent update to PageSpeed Insights focuses on improving mobile performance. You can learn more by reading about mobile analysis in PageSpeed Insights or by watching at Google I/O 2013 on Instant Mobile Websites.
Web Performance Best Practices
When you profile a web page with Page Speed, it evaluates the page's conformance to a number of different rules. These rules are general front-end best practices you can apply at any stage of web development. Page Speed provide documentation of each of the rules here, so whether or not you run the Page Speed tool — maybe you're just developing a brand new site and aren't ready to test it — you can refer to these pages at any time. Page Speed give you specific tips and suggestions for how you can best implement the rules and incorporate them into your development process.
About the performance best practices
Page Speed evaluates performance from the client point of view, typically measured as the page load time. This is the lapsed time between the moment a user requests a new page and the moment the page is fully rendered by the browser. The best practices cover many of the steps involved in page load time, including resolving DNS names, setting up TCP connections, transmitting HTTP requests, downloading resources, fetching resources from cache, parsing and executing scripts, and rendering objects on the page. Essentially Page Speed evaluates how well your pages either eliminate these steps altogether, parallelize them, and shorten the time they take to complete. The best practices are grouped into six categories that cover different aspects of page load optimization:
- Optimizing caching — keeping your application's data and logic off the network altogether
- Minimizing round-trip times — reducing the number of serial request-response cycles
- Minimizing request overhead — reducing upload size
- Minimizing payload size — reducing the size of responses, downloads, and cached pages
- Optimizing browser rendering — improving the browser's layout of a page
- Optimizing for mobileNew! — tuning a site for the characteristics of mobile networks and mobile devices
Make the Web Faster
Learn More
Analyze and optimize your website with PageSpeed tools
Leverage Google's infrastructure
Learn about Google's contributions to latest performance standards & protocols
Tutorials
There are many ways to make websites run faster. In this section, you can discover performance best practices that real web professionals employ in their everyday work. These practices have improved the user experience for millions of users and we hope they are useful for other web developers.
Web metrics: Size and number of resources
This article contains various statistics about web pages, including details about embedded resources such as images, scripts and stylesheets.
Use compression to make the web faster
Gzip compression helps reduce the time required to download web pages. This article takes a look at why not all users take advantage of compression.
Capturing and analyzing browser paint events using Page Speed Activity
Capture and analyze browser paint events using the Page Speed Activity Panel's paint snapshot feature.
Compressing your JavaScript with Closure Compiler
Speed download times for webpages by compressing your JavaScript with Closure Compiler.
CSS: Using every declaration just once
Using every CSS declaration only once is an effective way to reduce file size of style sheets. Because this is not a trivial optimization technique, you'll also need to adjust your editing workflow.
How gzip compression works
Learn how gzip compression works in a transaction between a web server and a web browser. Then, take a look at what gzip actually compresses, so that you can leverage compression in your markup.
HTTP caching
Web pages can load much faster on repeated visits if the resources come from the cache. Learn about two groups of HTTP headers that make all the difference.
Improving website performance with Page Speed
You can often reduce the number of bytes of a web page — and speed up the page's download — without changing its appearance or function. Discover three ways to reduce the size of web page content, using Page Speed.
Make the mobile web faster
A collection of best practices, tips, and resources for optimizing your pages for mobile.
Minimizing browser reflow
Improve browser rendering performance by minimizing operations that cause browser reflow.
Optimizing JavaScript code
JavaScript can make your web apps dynamic and interactive, but the client-side interpretation can introduce its own inefficiencies. Use these tips to optimize your JavaScript code.
Optimizing OpenSocial gadgets
Learn a few basic steps that gadget developers can take to improve the performance of their gadgets in iGoogle and on other OpenSocial enabled containers throughout the web.
Optimizing web graphics
Learn how to optimize your web illustrations, icons, and graphics for faster download on the web.
PHP performance tips
Speed up your existing PHP scripts with some simple changes recommended in these tips.
Prefetching resources
Downloading resources required for a page in advance makes them instantly available once requested, and can be an effective technique for reducing or even eliminating user-perceived network latency.
Properly including stylesheets and scripts
Combining external stylesheets and scripts, and correctly ordering them in the containing page, enables better parallelization of downloads and speeds up browser rendering time.
Reducing the file size of HTML documents
Omitting optional tags, leveraging HTML 5's shorter DOCTYPE, and a few other techniques can help reduce the file size and load time of your HTML documents.
Speeding up JavaScript: Working with the DOM
When working with Rich Internet Applications, we write JavaScript that updates the page by changing elements or adding new ones. This is done by working with the DOM, or Document Object Model, and how we do this can affect the speed of our applications.
UI messaging and perceived latency
To the typical user, speed doesn't only mean performance — it means the ability to use your website efficiently. Learn how to deliver effective UI messaging, a crucial part of keeping your users engaged and productive.
Using HTML 5 for performance improvements
In HTML, we can already reduce content size significantly by omitting optional tags. HTML 5, which is still under development, offers us a couple more options to decrease file size beside leaving out optional stuff. This article features some basic measures to reduce content size a bit more, plus the async and defer attributes useful to improve script execution.
