Proof that Website Speed Matters

Proof that Website Speed Matters

Written by P.J. Aitken

The early days of SEO were a veritable wild west, one where anything went and success was reserved for who took risks, went against the status quo, or were exceedingly fortunate. These days SEO is complicated, multi-faceted, uncertain and unforgiving. It’s built on assumptions, extrapolations, and experience — it’s a practice that is constantly evolving and leaves even its experts in the dark on occasion.

One of the many hotly debated points is whether or not page speed impacts search engine rankings. It’s something that had no bearing in those early days, but something that could play a significant role today.

The question is, can the speed of your site really impact on search engine placement, and if so, to what extent?

Does Speed Matter?

In 2010, Google announced that site speed would be factored into their search engine algorithm for the first time, with their announcement ostensibly coming after weeks of trials. 1 Load times also became a factor in establishing mobile rankings in July 2018 and throughout this time they made it abundantly clear that speed was important. 2

However, the notoriously vague search engine giant hasn’t released information concerning how much it affects the rankings or at what point a site’s speed is defined as acceptable. For that, we need to look elsewhere.

In 2013, Moz ran an in-depth study that found no correlation between page load speed and search engine rankings and similar results can be found in case studies conducted on major websites that were already getting a lot of traffic. 3 The only sites that seem to have seen a noticeable impact as a result of site speed improvements are sites that were very slow to begin with.

But there are other factors at play here, ones that suggest a fast website is not only important but essential.

Other Factors to Consider

Let’s suppose for a moment that Google doesn’t care all that much about site speed and is only interested in punishing sites that have really slow load times (as they have openly stated themselves in the past). Even if this was the case, there would still be several other issues, as a slow site can negatively impact SEO in more ways than one:

1. Bounce Rate

According to a poll by Think with Google the likelihood of a “bounce” (defined as a user who clicks away from a site without interacting with it) increases significantly for every second of load time. 4 The likelihood of a single user “bouncing” turns from 30% to 106% when the page takes an additional three seconds to load and from 30% to 123% if it takes an additional seven seconds. These load times are based on how long it takes for a page to become interactive, as opposed to how long it takes for a page to completely load (research suggests that the average “complete” load time is as high as 22 seconds for a mobile website, with the average “partial” load time at between 1 and 3 seconds).

The BBC has also previously stated that they lose as many as 10% of their users for every additional second that it takes for their and websites to load 5. When you consider that the BBC receives close to 19 billion page views a year that’s a lot of lost traffic. 6

Google hasn’t made their stance on bounce rate clear, but they have been open about the role that relevance and accessibility play, and a high bounce rate doesn’t look good for either of these factors. A higher bounce rate can also lead to a drop in ad revenue.

2. Conversions

The impact that page speed can have on conversions was thrust to the forefront in 2012 when a headline-grabbing study announced that Amazon could stand to lose $1.6 billion a year in sales if their site took just 1 second more to load. 7 8

This study was far from scientific and made a lot of assumptions, but similar studies have been conducted since and show similar results. 9 In 2016 noticed a 7% increase in conversions after they improved their server render time by 68%, while AliExpress saw a 10.5% order increase and a 27% conversion increase following an improvement in their load time. 10

This also ties in to what we discussed above about bounce rates — a user that remains on the site is more likely to convert than one who closes the page down before it loads.

3. Engagement

A happier user is a more engaged user, and a user more likely to subscribe to services, follow social media accounts, and generally become profitable for the website.

In 2016, the Financial Times overhauled their website and noticed a 30% increase in their subscriber base. 11 A year later, the social media network Pinterest improved their page speed by 40% and noted a 15% increase in organic traffic, in addition to an increase in conversions. 12 On the surface, this suggests that their rankings had improved, but it’s worth noting that a large percentage of their traffic is direct or from referrals.

What Does this Mean?

There is rarely any certainty where Google’s algorithm is concerned and there are still some questions left unanswered here. We can be certain of a few things though:

  • Painfully slow sites will be heavily penalized
  • Poor speed page can negatively impact other factors
  • Mobile speed seems to be more important than desktop speed

We can’t be certain what Google defines as “page load time” (whether it’s a fully rendered page or a stage known as “document complete”, which indicates a page that can be interacted with) or how much it punishes slow sites.

We can be sure of one other thing though, and that’s the fact that the odd byte won’t directly impact rankings. It could improve bounce rates and conversions, but as noted by Google trends Analyst John Mueller in 2016, “…optimizing on a millisecond basis is not going to affect anything in the search results”. 13

As a webmaster, you owe it to yourself to factor page speed into the equation and avoid painfully slow load times—the average internet user wants everything instant and Google is the same.

But you don’t need to stress over every single byte, not yet anyway. In November 2018, several months after announcing their mobile speed update, Google launched the latest version of its PageSeed Insights tool and this led many experts to conclude that they were preparing for a big algorithm change.

It is highly unlikely that slightly slow sites will be affected, but if you do have a painfully slow site and have avoided a ranking hit thus far, your time could be up in 2019.


  1. Google Blog – Using Site Speed in Web Search Ranking
  2. Google Blog – Using Page Speed in Mobile Search
  3. Moz – How Website Speed Actually Impacts Search Ranking
  4. Think With Google – Mobile Page Speed New Industry Benchmarks
  5. Creative Bloq – How the BBC Builds Websites that Scale
  6. The Guardian – BBC Websites Dominate the Market in Online News Views
  7. Fast Company – How One Second Could Cost Amazon 16 Billion in Sales
  8. Search Engine Land – Site Speed PPC Performance Can’t Ignore Slow Sites Anymore
  9. Velocity NY Jed Wood Ancestry User Centered Metrics
  10. ServerGuru – Page Loading Time a Factor in Google Rank
  11. Wall Street Journal – Financial Times Hopes Speedy New Website Will Boost Subscribers
  12. Pinterest Engineering – Driving User Growth With Performance Improvements
  13. The SEM Post – How Page Speed as a Ranking Factor Works

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