Why does website performance matter?

Google describe a delightful web experience as fast, integrated, reliable and engaging. This statement underpins the more technical aspects of measuring website performance.

Website visitors perceive performance delays differently, depending on their network and computer. For example, loading sites on a powerful desktop machine over a fast Wi-Fi connection commonly happens in under 1 second and users have grown accustomed to that. Loading sites on mobile devices with slow 3G connections can take a lot longer.

Website visitors expect smooth, responsive scrolling and quick load times from websites. Making your website fast is a process that starts with understanding what affects your website’s performance and how to use that information to measure and improve your website’s speed.

Don’t go off the R.A.I.L.

RAIL is a performance model that helps define specific goals for improving the user experience. The model breaks down the user’s experience into key actions (such as tapping, scrolling, and loading content) and provides a structure for thinking about performance in relation to each.

RESPONSE

By keeping the response time to user interactions less than 100ms, users feel the response was instantaneous. This applies to actions such as button clicks, content toggles or form controls. If the response time needs to be longer, provide feedback to the user to inform them.

ANIMATION

Web browsers need around 5-6ms to respond to frames in an animation, and with leeway the upper most limit for animation loading should be 10ms or less per frame. The aim is to create a smooth visual appearance for the animation so users do not notice the transition between frames.

IDLE

Utilise idle time to do the heavy lifting for the elements needing to load within the page. Keep the initial page load as light as possible, and then utilise the time when the user is scanning the page contents to do background work. if a user interacts with the page during this time, their interaction must then take the highest priority.

LOAD

It would be of no surprise to learn that online users have short attention spans. Whilst in the discovery phase of the user journey, a visitor might open multiple websites to scan for information. If the page loads slowly, their attention moves to the next result, or a different task. Websites that load quickly have been proven to have longer visitor session times and lower bounce rates, making the effort of optimising load times highly valuable for any business that relies on their website traffic to drive revenue.

Measuring your website performance

Luckily, you don’t have to be a website developer to measure (and improve) your website performance. Google offer tools to undertake this process, linking to an extensive library of information to guide you through each task. Google offer three ways you can test your website performance.

Pagespeed Insights

Pagespeed Insights is a browser based tool from Google, using their open aource automated measurement tool Lighthouse. The Lighthouse API performs tests on a given domain name, and returns results to Pagespeed Insights, where each category within the report are presented with a score, weighted based on the importance for web performance (weighting varies ocassionally as Google updates their performance metrics).

First Contentful Paint 10%
Speed Index 10%
Largest Contentful Paint 25%
Time to Interactive 10%
Total Blocking Time 30%
Cumulative Layout Shift 15%

So, in order to get the most impact from improving web performance, it would be wise to prioritise the highest weighted criteria.

Total Blocking Time 30%
Largest Contentful Paint 25%
Cumulative Layout Shift 15%
First Contentful Paint 10%
Speed Index 10%
Time to Interactive 10%

As you can see, the most important category in the performance report is total blocking time. This reinforces why it is highly important to minimise the page load.

Further reading

Web Fundamentals

Fast Load Times

Website Performance Scoring

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Joff Crabtree

Joff Crabtree

Joff is a digital innovation specialist guiding data-driven decision making to transform business potential.

Digital Debrief

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