Google considers website speed as one of its most important ranking factors. So optimizing for it is needed to provide a better user experience.
If the user gets frustrated with waiting for a slow website to load, they will simply move to a faster alternative.
So in order to offer a smooth user experience, Speed Index helps us to quantify the speed of the website.
But what is a Speed Index exactly and what role does it play in technical SEO? Let’s explore..!
What is a Speed Index?
Speed Index (SI) is a performance metric which measures how quickly a web page loads its visible content.
It determines the average amount of time at which the visible content of the page is displayed during the loading process. The time is expressed in seconds.
This metric prioritizes the content that appears in the viewport without scrolling. It mainly focuses on the user’s visual experience.
Faster visual loading is indicated by a lower Speed Index score which corresponds to a better user experience.
What is a Good Speed Index Score?
The score of the speed index is expressed in seconds (s). Google’s guidelines provide the following threshold of Speed Index scores:
- Fast – 0 to 3.4 s
- Moderate – between 3.4 s to 5.8 s
- Slow – Above 5.8 s
Achieving a speed index score less than 3.4 s is considered ideal. But, a decent user experience can still be obtained with a score lower than 5.8 s.
How is the Speed Index calculated?
The Speed Index is calculated by measuring the Cumulative Layout Shift of the page over time.
It takes into account how much the page’s layout changes as it loads, and how quickly those changes occur.
How is the speed index calculated is as follows,
Step 1: Baseline Layout – The initial state of the page’s layout is recorded.
Step 2: Element Loading – When the elements of the page get loaded, the browser updates the page’s layout to accommodate the new content. The elements can be images, text or JavaScript.
Step 3: Layout Shift – This is the measurement of the variation between the original baseline layout and the updated layout. This is referred to as Layout shift.
Step 4: Cumulative Layout Shift – This refers to the total amount of layout shift occurring over the course of time on the page. The Speed Index is this total value.
Thus Higher Speed Index indicates,
- The layout of the page changes more frequently or takes longer to stabilize.
- When the elements load, the user experiences visual instability
- This is distracting and negatively impacts user experience.
Lower Speed Index indicates,
- The layout of the page is more stable and the elements load more quickly.
- When the elements load, the user will less-likely experience visual disruptions.
- This leads to more positive and engaging experience.
6 Effective Methods to Optimize Speed Index:
1.Optimize Images and Videos
The elements of the web page that require the most of the resources are Images and Videos.
They have the power to slow down rendering and increase the speed index score if not optimized properly.
Solutions to Optimize Images and Videos:
- The images should be properly sized to adapt different devices using size attributes. By doing so, the browser will not load the large and unnecessary images on smaller screens.
- Reduce the image file size with the help of image compression tools without sacrificing the quality. The compressed images will load faster and the speed index time gets reduced.
- WebP is the modern image format which offers better compression without losing the quality. WebP format helps to deliver smaller images that load faster.
- Make use of Lazy Loading to enable the images and videos to load only when the user scrolls to them. So it will allow the above-the-fold content to load faster and improve speed index.
2.Minimize Render Blocking Resources
The render blocking resources like CSS and JavaScript files delays the browser from displaying the content. This is because, the browser needs to download, parse and execute these resources, before it renders the page.
When the large CSS or JavaScript files get loaded before the important content, it blocks the page from rendering. This leads to a slower speed index.
Solutions to Minimize Render Blocking Resources:
- The non-critical resources should be loaded asynchronously or deferred. This will allow the browser to prioritize the visible content first.
- The loading of non-critical JavaScript files should be delayed using the defer or async attributes. So the browser will not wait for the scripts to load and continue rendering the page.
- The code that is not needed for the first rendering of the page should be removed or reduced.
- The essential CSS styles which are needed for the above-the-fold content should be moved directly into the HTML file. So the significant parts of the page will be rendered without requiring external CSS requests.
3.Optimize Web Fonts
Web Fonts requires additional requests to get downloaded. So it causes delay in rendering text content.
Because of this, until the fonts are fully loaded, this causes the text to remain invisible (i.e) Flash of Invisible Text (FOIT) or unstyled (i.e) Flash of Unstyled Text.
Solutions to Optimize Web Fonts:
- Use system fonts like Arial, Times New Roman or Helvetica. These fonts need not to be downloaded.
- While the web font is being loaded, use the “font-display: swap” property in CSS to show a fall back font.
- So if the web font takes longer to load, the text will appear instantly.
For a deeper dive on this issue, check out our guide on How to avoid Layout Shifts caused by Web Fonts?, which explains specific techniques to minimize layout shifts and improve Speed Index.
4.Optimize Server Response Time
The Time To First Byte (TTFB) (i.e) the time taken by the server to respond to a request impacts the speed at which the page starts loading.
Thus the rendering process will be delayed by a slow server response which will have a negative effect on the speed index.
Solutions to Optimize Server Response Time:
- Switch to a faster hosting solution like virtual private server (VPS) or dedicated server, if you feel your server response time is slow. Cloud-based hosting solutions like Amazon Web Services (AWS) or Google Cloud offer better performance.
- Optimize the database or use more efficient code to reduce the number of database queries.
- The server-side caching should be implemented to store the copies of the web pages. So the need for the server to dynamically generate content for each request gets reduced.
5.Use Browser Caching
Caching stores the previously loaded resources in the user’s browser locally. So when the user revisits the page or navigates to a new page on the site, the cached resources are retrieved without requesting them again from the server. This results in a higher Speed Index and faster page renders.
Solutions to use browser caching:
- Set the cache expiry headers. This means the HTTP headers should include caching rules for resources like CSS, JavaScript and Images.
- These cache-control headers help the browser to determine when to reuse cached resources.
- The optimal caching rules should be implemented with the help of tools like W3 Total Cache for WordPress or manual cache control via .htaccess for Apache servers.
6.Pre-Load Key Resources
The browser prioritizes the important resources like fonts, key images or CSS files with preloading. So during the page rendering they are available as soon as needed. This makes the page visually complete faster and reduces delays.
Solutions to Pre-Load Key Resources:
- Preload Web Fonts. This is because the browser has to fetch the web fonts before displaying text. These web fonts significantly delay the rendering.
- So in the rendering process, use the rel=”preload” attribute to load the fonts early.
- To apply the CSS styles immediately, preload the essential CSS, specifically for the above-the-fold content.
- During page load, the important images such as logos or hero banners should be preloaded to appear sooner.
Conclusion
In conclusion, the speed index can be improved by addressing several aspects of the performance of the website. It includes optimizing the content delivery mechanism on the server side to streamlining the resource loading process on the client side.
The content of the website can be displayed quickly and efficiently by implementing the strategies outlined above.
Make use of tools like Google PageSpeed Insights or Lighthouse to monitor the speed index regularly. These tools help to track improvements and maintain a low speed index.
By doing so, get your SEO Performance boosted and user experience enhanced.
