February 4, 2021
When Google announced that site speed would impact search ranking, thousands of teams across the globe started to get to work. Each, asking themselves the same question: How will this affect my sites SEO?
The shared answer to this question up until now has been: we have no idea. The reason for this? The closely coveted Google search algorithm could be gamed, so official information up until now has been thin.
Over the last few years, we at Calibre have built up a library of performance knowledge by observing our customers and the challenges that they and the larger web performance community face.
This site speed and search ranking guide will help you answer the most common questions about how speed impacts SEO.
Over the last few years, Google has introduced numerous significant changes to its search indexing and ranking algorithms that prioritise speed:
No matter what devices your customers use, Google will evaluate your site from a mobile perspective. If it’s slow to load, doesn’t fit properly on the phone, jumps around during page load, or generally performs in a way that causes users grief: Google will ding you for it.
Improving user experience (and consequently, speed) is now required as a part of search engine optimisation and improving rankings.
Google Chrome browser collects speed data directly from its users and sends it back to a Google-owned private data store. As you navigate the web, Chrome collects the following:
Google collects this data with two caveats:
After speed data is cleaned of Personally Identifiable Data (PII) it is stored, aggregated, and surfaced publicly as the Chrome User Experience Report (aka CrUX). The CrUX dataset is then used by Google’s Search and Ranking Algorithm.
Google evaluates pages based on content, relevance, quality, engagement metrics and many other factors.
In terms of page experience, pages are judged in the following ways:
In addition to the factors above, a new set of metrics, called Core Web Vitals, will be used as page ranking signals for your pages, starting May 2021.
Core Web Vitals are a set of recognised metrics that describe different aspects of user experience:
To give your site the best chance of ranking above your competitors, you should to ensure that your Core Web Vitals fall within the recommended thresholds.
Google’s Chrome User Experience Report (CrUX) gives free public access to aggregated site speed metrics collected from real Chrome users in the field.
CrUX includes Core Web Vitals metrics from phones and desktop devices, based on users who have visited your site within a given month.
Google provides a few ways for you to access CrUX data:
Each of these methods are free but require varying levels of coding know-how.
CrUX data is a 28-day rolling aggregation, so any changes made to your site will take at least a full month before they're clearly reflected in user-experience metrics.
In order to combat the long feedback loop, use synthetic based tools (like Calibre, PageSpeed Insights, or Lighthouse) to test pages as work is developed and rolled out.
Many teams believe that Google uses the PageSpeed Performance Score to rank your site. This is false. PageSpeed Performance Score has no direct bearing on your search ranking (either does Lighthouse Performance Score).
As explored earlier, Google evaluates your site speed for search ranking based on real Chrome user data.
Using tools like PageSpeed or Lighthouse helps understand how your pages perform. It’s important to note that the metrics they return are only signals—there’s no immediate loss of Google juice if your Performance Score drops from 90 to 85.
Performance Score is a short-hand abstraction used to describe overall page speed using a single measurement quickly.
Any significant improvement made to a site’s Performance Score will likely improve overall page speed; however, no single metric can accurately describe or guarantee a great user experience for every visitor.
Instead of the Performance Score, organisations should use Core Web Vitals as KPIs. Development teams will likely rely on Core Web Vitals alongside a set of specialised diagnostic metrics to break down user-experience into granular areas of focus and address specific issues.
Now that we have established how speed is measured for SEO purposes, the question quickly shifts to “How should we keep track of speed?”.
Improving speed can be difficult, time-consuming and requires consistent dedication. Your success will depend on the commitment your team makes to speed.
To ensure your sites and products are at their best, you should strongly consider the following:
From now on, you will need a permanent monitoring system that provides your team with tools to track site speed and achieve the goals above. There are many ways to run Lighthouse yourself, but we recommend using a reliable, comprehensive monitoring tool to avoid the headaches of building and maintaining a solution yourself.
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Engineering Manager at Google Chrome