Speed Index (Lighthouse)

Creating a fast website? Among other things, a low Speed Index is very important in this case. What is a Speed Index and why does it play a big role in your website? You can read about that here!

What is Speed Index?

Speed Index is a measurement tool for a Web site. It determines the load time of visible parts on the page. Lighthouse, Google’s open source tool, provides this and other metrics to measure and improve the performance of a Web site.(1)(2)

The importance of a low Speed Index

The metric Speed Index is one of 6 ways you measure a website’s performance. Speed Index measures the time it takes for the visible parts of a page to load. Lighthouse gives you insight into a page’s Speed Index: it calculates the visual progression between various frames. With Speed Index, the shorter the time, the better.

Speed Index is one of the metrics that carries the most weight, along with Time to Interactive (TTI) and First Contentful Paint (FCP). Among other things, Javascript is a possible reason that the load time for visible parts of a page is high. Loading unnecessary JavaScript files takes extra time.

The impact of Speed Index on SEO

The Speed Index certainly has an impact on the SEO of a website or page. Speed is an important factor in SEO and with improving the Speed Index, along with the TTI and FCP it is possible to optimize the website. One way to do this is with Lighthouse, the open source tool that offers these metrics. This will give you insight and opportunities to make certain changes.

My advice

We recommend using Lighthouse to gain insight into the Speed Index and other important issues that affect ranking in search results. Among other things in the use of Magento 2, Lighthouse is definitely recommended. A developer knows good solutions for improving scores, for example, through modifications in JavaScript.

The most complete book on website speed

I’ve written so much about speeding up websites and everything involved that I like to divide it into different sections; general, tools, speed improvement points and tips. Feel free to see and consult all the links below to learn more about tools and tips for speeding up your website.



Verbter points for speed

General tips


  1. Speed Index. (2019, May 2). Chrome For Developers. https://web.dev/speed-index/
  2. Speed Index. (2019b, May 2). Chrome For Developers. https://developers.google.com/web/tools/lighthouse/audits/speed-index

Frequently Asked Questions

What is Speed Index Lighthouse?

Speed Index is an open-source tool from Google that can be used to measure and improve a website’s performance. Among other things, Speed Index lets you determine the load time of the various visible parts of a Web page.

What is the impact of Speed Index Lighthouse on SEO?

Performance is an important component in SEO. With Speed Index Lighthouse, you can measure and improve them. The better your website loads, the higher the ranking Google will give your site in search results.

Senior SEO-specialist

Ralf van Veen

Senior SEO-specialist
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I have been working for 10 years as an independent SEO specialist for companies (in the Netherlands and abroad) that want to rank higher in Google in a sustainable manner. During this period I have consulted A-brands, set up large-scale international SEO campaigns and coached global development teams in the field of search engine optimization.

With this broad experience within SEO, I have developed the SEO course and helped hundreds of companies with improved findability in Google in a sustainable and transparent way. For this you can consult my portfolio, references and collaborations.

This article was originally published on 3 April 2024. The last update of this article was on 3 April 2024. The content of this page was written and approved by Ralf van Veen. Learn more about the creation of my articles in my editorial guidelines.