Measuring Websites With Mobile-First Optimization Tools

Measuring Websites With Mobile-First Optimization Tools

Measuring Websites With Mobile-First Optimization Tools

Jon Raasch


Performance on mobile can be particularly challenging: underpowered devices, slow networks, and poor connections are some of those challenges. With more and more users migrating to mobile, the rewards for mobile optimization are great. Most workflows have already adopted mobile-first design and development strategies, and it’s time to apply a similar mindset to performance.

In this article, we’ll take a look at studies linking page speed to real-world metrics, and discuss the specific ways mobile performance impacts your site. Then we’ll explore benchmarking tools you can use to measure your website’s mobile performance. Finally, we’ll work with tools to help identify and remove the code debt that bloats and weighs down your site.

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How would you design a responsive car configurator? How would you deal with accessibility, navigation, real-time previews, interaction and performance? Let’s figure it out. Read article →

Why Performance Matters

The benefits of performance optimization are well-documented. In short, performance matters because users prefer faster websites. But it’s more than a qualitative assumption about user experience. There are a variety of studies that directly link reduced load times to increased conversion and revenue, such as the now decade-old Amazon study that showed each 100ms of latency led to a 1% drop in sales.

Page Speed, Bounce Rate & Conversion

In the data world, poor performance leads to an increased bounce rate. And in the mobile world that bounce rate may occur sooner than you think. A recent study shows that 53% of mobile users abandon a site that takes more than 3 seconds to load.

That means if your site loads in 3.5 seconds, over half of your potential users are leaving (and most likely visiting a competitor). That may be tough to swallow, but it is as much a problem as it is an opportunity. If you can get your site to load more quickly, you are potentially doubling your conversion. And if your conversion is even indirectly linked to profits, you’re doubling your revenue.

SEO And Social Media

Beyond reduced conversion, slow load times create secondary effects that diminish your inbound traffic. Search engines already use page speed in their ranking algorithms, bubbling faster sites to the top. Additionally, Google is specifically factoring mobile speed for mobile searches as of July 2018.

Social media outlets have begun factoring page speed in their algorithms as well. In August 2017, Facebook announced that it would roll out specific changes to the newsfeed algorithm for mobile devices. These changes include page speed as a factor, which means that slow websites will see a decline in Facebook impressions, and in turn a decline in visitors from that source.

Search engines and social media companies aren’t punishing slow websites on a whim, they’ve made a calculated decision to improve the experience for their users. If two websites have effectively the same content, wouldn’t you rather visit one that loads faster?

Many websites depend on search engines and social media for a large portion of their traffic. The slowest of these will have an exacerbated problem, with a reduced number of visitors coming to their site, and over half of those visitors subsequently abandoning.

If the prognosis sounds alarming, that’s because it is! But the good news is that there are a few concrete steps you can take to improve your page speeds. Even the slowest sites can get “sub three seconds” with a good strategy and some work.

Profiling And Benchmarking Tools

Before you begin optimizing, it’s a good idea to take a snapshot of your website’s performance. With profiling, you can determine how much progress you will need to make. Later, you can compare against this benchmark to quantify the speed improvements you make.

There are a number of tools that assess a website’s performance. But before you get started, it’s important to understand that no tool provides a perfect measurement of client-side performance. Devices, connection speeds, and web browsers all impact performance, and it is impossible to analyze all combinations. Additionally, any tool that runs on your personal device can only approximate the experience on a different device or connection.

In one sense, whichever tool you use can provide meaningful insights. As long as you use the same tool before and after, the comparison of each should provide a decent snapshot of performance changes. But certain tools are better than others.

In this section, we’ll walk through two tools that provide a profile of how well your website performs in a mobile environment.

Note: If can be difficult to benchmark an entire site, so I recommend that you choose one or two of your most important pages for benchmarking.


One of the more useful tools for profiling mobile performance is Google’s Lighthouse. It’s a nice starting point for optimization since it not only analyzes page performance but also provides insights into specific performance issues. Additionally, Lighthouse provides high-level suggestions for speed improvements.

Lighthouse audit tab
Lighthouse in the Google’s Web Developer Tools. (Large preview)

Lighthouse is available in the Audits tab of the Chrome Developer Tools. To get started, open the page you want to optimize in Chrome Dev Tools and perform an audit. I typically perform all the audits, but for our purposes, you only need to check the ‘Performance’ checkbox:

Lighthouse audit selection
All the audits are useful, but we’ll only need the Performance audit. (Large preview)

Lighthouse focuses on mobile, so when you run the audit, Lighthouse will pop your page into the inspector’s responsive viewer and throttle the connection to simulate a mobile experience.

Lighthouse Reports

When the audit finishes, you’ll see an overall performance score, a timeline view of how the page rendered over time, as well as a variety of metrics:

Lighthouse performance audit results
In the performance audit, pay attention to the first meaningful paint. (Large preview)

It’s a lot of information, but one report to emphasize is the first meaningful paint, since that directly influences user bounce rates. You may notice that the tool doesn’t even list the total load time, and that’s because it rarely matters for user experience.

Source: Smashing Magazine