Evan X. Merz

musician / technologist / human being

How to conquer Google Core Web Vitals

In 2021, Google finally launched their long awaited Core Web Vitals. Core Web Vitals are the measurements that Google uses to measure the user experience (UX) on your website. These include metrics tracking things like how long the page takes to load images, how long it takes to become interactive, and how much it jitters around while loading.

Core Web Vitals are important to all online businesses because they influence where your site appears on Google when users are searching for content related to your site. They are far from the only consideration when it comes to search engine optimization (SEO), but they are increasingly important.

In this article, I'm going to give you a high level overview of how you can get green scores from Google's Core Web Vitals. We're not going to dig into implementation level details, yet, but we will look at the general strategies necessary to optimize the scores from Google.

This article is informed by my experience optimizing Core Web Vitals scores for the websites I manage and develop professionally. It's also informed by my study and experimentation on my own websites and projects.

Prepare for a long battle

Before we begin, I want to set your expectations properly. On any reasonably large website, Core Web Vitals scores cannot be fixed in a night, or a weekend, and maybe not even in a month. It will likely take effort each week, and in each development project, to ensure that your scores get to the highest level and stay there.

This is the same expectation we should have for any SEO efforts. It takes time to get things right in the code, the architecture, and in the content. All three of those things must work together to put your site on the first page of Google search results for high volume search terms.

In my experience, a successful SEO operation requires coordination of web developers, SEO experts, writers, and whoever manages the infrastructure of your website.

1. Understand Core Web Vitals

The first step to conquering Core Web Vitals is to understand what they are measuring. So get access to Google Search Console, and start looking at some reports. Use PageSpeed Insights to start looking at the values that Google is actually calculating for your site.

Don't be scared if your scores are really low at first glance. Most sites on the internet get very low scores because Google's standards are incredibly high.

You should see some aronyms that represent how your site did on key metrics. There are four metrics that are used to calculate the Core Web Vitals score for a page.

  • LCP = Largest Contentful Paint.
    • The LCP of a page is how long it takes for the largest thing to be shown on screen. Typically this is the banner image on a page, but PageSpeed Insights can sometimes get confused if you use header tags in the wrong places.
  • FCP = First Contentful Paint.
    • The FCP of a page is how long it takes for anything to appear on screen.
  • CLS = Cumulative Layout Shift.
    • The CLS is a measure of how much elements on the page jitter around while the page is loading.
  • FID = First Input Delay.
    • FID is how long it takes for the page to respond to a click.

2. Make the right architecture decisions when starting a new site

Most people can't go back in time and choose a different platform for their site. Most people are stuck with the architectural decisions made at the beginning of the project. If you're in that category, then don't fret. The next section will talk about how you can maximize existing infrastructural technologies to get the maximum performance out of your website.

On the other hand, if you are starting from scratch then you need to critically consider your initial architectural decisions. It's important to understand how those architectural decisions will impact your Core Web Vitals score, and your search ranking on Google.

Client side rendering vs. Sever side rendering

The most important decision you have to make is whether you will serve a site that is fully rendered client side or a site that renders pages on the server side.

I want to encourage you to choose a site architecture that is fully client side rendering, because client side rendering provides huge benefits when it comes to both scaling and SEO, and the drawbacks previously associated with client side rendering are no longer relevant.

Imagine the typical render process for a webpage. This process can be broken down into many steps, but it's important to realize that there are 3 phases.

  1. The server fetches data from a data store.
  2. The server renders the page.
  3. The client renders the page.

Steps 1 and 3 are unavoidable. If you have a backend of any complexity, then you must have a data store. If you want users to see your website, then their web browsers must render it.

But what about step 2? Is that step necessary? No. Even worse is the fact that it's often the most time-consuming step.

But if you build your site as a client-side js/html/css bundle that uses an API on the backend, then you can cut out the server side rendering entirely. If you want to maximize your site's Core Web Vitals scores, and hence your SEO, then you should cut out the server side rendering step if possible. Adding that step is inherently slower than strategies that eliminate it.

This means that platforms that are used for server side rendering are probably something to avoid in 2022 and beyond. So Ruby on Rails is probably a bad choice, unless you're only using it to build an API. Similarly, Next.js is probably a bad choice, unless you are only using it to generate a static site.

You should also look at benchmarks for various website architectures. You will see that vanilla React/Vue/Javascript sites generally outperform server side rendered sites by a wide margin.

But isn't a client side rendered site bad for SEO?

If someone hasn't done much SEO lately, then they may come up with this counterargument, that using client side rendering is bad for SEO. Up until around 2017, Google didn't run the javascript on web pages it was scanning. If the javascript wasn't executed, then a purely client side rendered page would show up as an empty page and never rank on Google. We had to come up with lots of workarounds to avoid that fate.

Since 2017, however, Google does run the javascript on the page. So having a purely client-side rendered site is perfectly fine.

Server side rendered sites are also harder to scale

I've scaled several websites in my career, so I can tell you that it's much more difficult to scale a server side rendered website than one that isn't server side rendered. To scale on the server side requires a complex balance of caching, parallelization, and optimization that is entirely unnecessary if your site is rendered client side.

It's true that you would still have to scale the API on the server side, but that's true in both cases.

3. Maximize mature web technologies

But what if you can't change the fundamental architecture of your website? Are you stuck? No. There are a number of web technologies that exist to mitigate the performance impact of various architectural decisions.

  1. Use a Content Distribution Network, especially for images. Take a look at services like ImgIX, which can optimize your images and play the role of a CDN. Other commonly used CDNs include CloudFront and CloudFlare.
  2. Optimize your cache layer. Try to hit the database as rarely as possible. The API that backs your site will get bottlenecked by something. Quite frequently, that something is your database. Use a cache layer such as REDIS to eliminate database queries where possible.
  3. Use geolocated servers. The CDN should take care of serving content from locations near your users, however, if requests are ever getting back to your web servers, make sure you have servers near your users.
  4. Enable automatic horizontal scaling of your server. You need to be able to add more servers during high traffic times, such as the holidays. To do so requires parallelizing your server code, and handling session across multiple servers. There are many ways to mitigate those problems, such as the sticky sessions feature offered by Heroku. You need to be able to scale horizontally at least on your API, if not on the servers that serve your site.

4. Monitor the results

Finally, you need to monitor Google Search Console every day. Google Search Console is one of the first things I check every time I open my work computer to begin my day. Make this a habit, because you need to be aware of the trends Google is seeing in the user experience on your site. If there is a sudden issue, or things are trending the wrong way, you need to proactively address the problem.

You should also use other site monitoring tools. Google's scores are a running 28 day average. You need a response time faster than 28 days. So I encourage you to set up a monitoring service such as Pingdom or Status Cake, which will give you real time monitoring of website performance.

Finally, you should run your own spot checks. Even if everything looks okay at a glance, you should regularly check the scores on your most important pages. Run PageSpeed Insights or Web Page Test on your homepage and landing pages regularly. Make sure to schedule time to take care of the issues that arise.


To conquer Google Core Web Vitals requires coordination of the effort of many people over weeks or months of time, but with a rigorous approach you can get to the first or second page of Google search results for high volume search terms. Make sure to spend time understanding Google Core Web Vitals. Ensure that the critical architectural decisions at the beginning of a project are in line with your long term goals. Maximize your use of mature web technologies to mitigate architectural issues. And monitor your site's performance every day.

With these strategies you can take your site to the next level.