Why Optimize Web Speed?

Web speed matters. Not just because Google says so.

The human mind's threshold for recognizing an interface's immediate response hovers in the low hundreds of milliseconds. Most websites today struggle to meet this mark upon loading, but every improvement counts.

Speeding up your website is likely to boost conversions—a claim backed by numerous case studies. Google's decision to favor fast websites means that speed can also enhance your traffic or even affect your advertising costs.

Google supports fast websites because speed impacts conversions. Also, because the human mind isn't infinitely patient.

Let’s first delve into the crux of the matter, rooted in the psychology of user patience with interfaces.

Psychology#

In 1968, R. B. Miller conducted the first tests to determine how users of the era's mainframe computers perceived terminal interface response times. Little did he know that his study would remain one of the most cited in the field over fifty years later.

Among other findings, his work pinpointed the magical threshold where interface reactions are perceived as immediate—around 100 milliseconds.

Mr. Miller would likely be quite surprised that even in 2020, we still struggle to load and render websites without making users impatient. As users, we all know that achieving hundreds of milliseconds with websites is a rather distant goal.

While technology has advanced significantly from mainframe terminals to modern web on smartphones, human psychology has not.

Yet, from the setup of the human mind, it follows that if you speed up the user interface, it will better achieve its goals.

Impact on Conversions#

The connection between web speed and conversion rates is a fact derived from R. B. Miller's findings and others, as well as practical case studies that have mushroomed over the last decade.

All studies demonstrate that speed improvements have positively impacted the business or goals of the website owner.

Bounce Rate#

"Bounce rate" is one of the most watched general analytics metrics. The belief is that by speeding up the initial rendering of the website, we also improve the bounce rate.

Correlation between speed and bounce rate on the Vzhůru dolů website (Source: SpeedCurve)

For examples of the impact of speed on bounce rate, let's explore the world:

• 53% of visits are likely to be abandoned if a page takes longer than 3 seconds to load. One of the most famous case studies comes from DoubleClick in 2016, now part of Google. (Source)
• On Radins.com, they improved the speed of the first screen rendering on desktops, reducing the bounce rate by 25%. (Source)

Pageviews#

In some industries, particularly those fueled by advertising, the number of pageviews determines business success or failure.

"At the BBC, we noticed that for every second delay in page loading, 10% of users leave. If the BBC website slows down due to loading, certain features automatically disable to boost speed again."

— Matthew Clark, lead technical architect at BBC

What case studies do we know about the impact of speed on "pageviews"?

• When Shopzilla reduced page load time by five seconds, they achieved a 12% better conversion rate and a 25% increase in pageviews.
• At Financial Times, adding a one-second delay to each page view resulted in a 4.9% drop in pageviews. A three-second delay led to a 7.2% drop. (Source)

Conversion Rate#

When speed improves, conversion rates tend to follow suit. If you run an e-commerce site, this will interest you. With our clients, it's usually challenging to isolate the impact of speed optimization from other influences, but we got lucky once.

Our Martin Michálek helped Czech price comparison site Srovname.cz increase mobile conversion rates by 25% through speed improvements - Source

• Deloitte Digital demonstrated conversion growth on 37 brand websites with a mere 100 ms speed improvement. (Source)
• As early as 2012, Walmart calculated that every second of homepage speed improvement boosts their web conversions by 2%. (Source)

There are plenty more case studies worldwide, nicely compiled on wpostats.com.

As the numbers show, speed impacts a range of crucial metrics. This is why Google has decided to focus on this easily measurable factor of user experience.

The Google Argument#

Occasionally, we witness conversations like this:

— "And why do you intend to address speed?"

— "Google wants us to"

These dialogues might suggest that the entire field of web speed is built on the outcomes of a few internal corporate meetings at Googleplex. We imagine several managers, engineers, and above all, one large crystal ball present.

Are Google's recommendations for web speed built on shaky ground? Nothing could be further from the truth.

The world's largest search engine employs exceptional technology speed experts and researchers backed by data. A recent example is the text The Science Behind Web Vitals, which illustrates the data foundations of new metric recommendations.

Google, simply put, relies on data, which increasingly highlights the connection between a good user experience and speed of loading and interaction.

Web Vitals and Page Experience Signal#

In a recent blog post Evaluating page experience for a better web, Google announced they are working on a new "Page Experience" ranking signal, where speed will play a significant role.

Google's "Page Experience" signal focuses on security, user experience, and speed.

This isn't the first time the search engine has announced its focus on speed, but it is the first time they've openly stated how they will measure it. They will focus on Web Vitals metrics, gathered directly from Chrome users and stored in the Chrome UX Report.

The crucial speed metrics for every website—Core Web Vitals.

Google will roll out the new signal throughout 2021, so it wouldn't hurt to prepare.

With our clients, we've already focused on Web Vitals. Let’s look at the individual metrics and supplement them with some of our successful optimizations.

Core Web Vitals optimization on Shoptet accelerated the deNatura.cz e-shop and increased Google traffic by 17%.

LCP (Largest Contentful Paint):

We helped the ČistéDřevo.cz e-shop identify backend issues. After adjustments, the LCP metric improved significantly.

INP (Interaction to Next Paint):

We assisted Sazka in identifying JavaScript performance issues caused by code in Google Tag Manager, negatively affecting the INP metric.

CLS (Cumulative Layout Shift):

During our collaboration with Pet Hardware, our Michal Matuška identified and eliminated unwanted layout shifts during rendering.

Google Ads and Mobile Speed Score#

If you invest in Google-operated advertising, you're likely familiar with the Mobile Speed Score, which Google uses to evaluate your campaign's target pages.

Speed score affects the price and position of your ads, so it's certainly worth focusing on it.

During one phase of our collaboration with our largest client, Livesport.cz, which offers fast sports results service, their excellent team managed to significantly improve the First Contentful Paint (FCP) with our advice: Development of the FCP metric on Livesport.cz among users till February 2020.

The subsequent improvement in Speed Score in Google Ads was more than gratifying:

	August 2018	January 2019
Europe	4-7	9-10
Japan	1-2	10
Africa	1-2	6-7
Australia	1	7-9
Brazil	1-2	7

Impact on Search Engine Rankings#

Before Google implements the Page Experience signal, the direct impact of web speed on SEO will remain a topic of lengthy discussion.

Speed cannot easily be isolated from other signals, and a study of the correlation between speed and search engine rankings would require comparing practically identical websites. Once we find such sites, we'll let you know.

Curious about our opinion? From all of Google's communications, it's clear that they consider speed an important signal. So being significantly slower than your competition is something we would certainly advise against.

If we set aside psychological and business reasons for speed and focus on SEO, the community agrees on one thing—it's good to have a fast server.

Correlation of TTFB (Time To First Byte) with Google rankings. - Source

TTFB metric, or simply server and infrastructure speed, is crucial not only for overall web speed but likely also for page ranking and "crawl budget"—the number of pages Google can process from your site.

Our recommendation to focus on the backend for this globally operating client significantly improved metrics.

Server speed, as well as client-side code, also impacts another factor evaluated by search engines—Dwell Time, the time between clicking from search results to your page and returning back.

Backend optimization is thus a key discipline.

How to Start Addressing Web Speed?#

There are plenty of options for where to start. The approach is always the same. The most important thing is to know where you stand, monitor trends over time in various contexts, and identify the right opportunities for improvement:

1. Measure your speed, ideally alongside your direct competition in our web speed tester.
2. Monitor your web speed regularly using monitoring.
3. The tester will measure the speed of tested websites daily, so save the URLs of your tests or sign up, and we'll send you a monthly status report.

If you find you have speed reserves, order a web speed audit, which includes tailored advice for your project. Or simply get in touch – info@pagespeed.cz.

Data Instead of Promises#

The Srovname.cz website saw a 25% increase in mobile conversions. Read about our approach and the specific adjustments that led to this in the case study.