5 ways to improve your Core Web vitals

“If only I could simply wave my wand and have a super fast website!” This has probably crossed your mind as well, right? Optimizing site speed and user experience is a lot of work and gets technical — and complicated — really fast. Most site owners or managers quickly need to talk to their developers to get stuff done. Now, the new Core Web Vitals metrics give you more insights and pointers at what to fix. Let’s go over five things you can do to improve your Core Web Vitals score.

On November 11, 2020, Google announced that the Page Experience ranking factor will roll out in May 2021.

Table of contents

First, a disclaimer

Look, there’s not one thing that’s guaranteed to fix one specific issue. You have to take a broader view of optimizing your site. A lot of little fixes make up big results. So, while I’ll give you five things you can work on here, this is nowhere near definitive. Even Google says many elements work together to come up with scores, so it’s hard to pinpoint if you do this, then that score will go up.

What Google does give you, is insights into what’s slowing stuff down or what’s hurting the user experience. Many tools also give advice on how to fix stuff. Web.dev/measure, for instance, doesn’t do in-depth results, but it does give you an idea of what the impact of a particular fix is.

Google’s Web.dev/measure tool gives you an idea of the impact a fix can have

Google’s upcoming page experience update

We’ve published a couple of articles about Google’s page experience update — coming in May 2021 —, so you can start here if you need more background information:

Five things you or your developer can do

Over the years, there’s been constant talk about the importance of site speed and user experience. But while there’s a ton of material out there on how to optimize your site, putting that knowledge into practice is hard. These past few months, Google once again put speed front and center with the page experience update happing next year. To help you get ready for that, it developed tools to give you insights and a lot of documentation to read.

For a lot of issues, the advice hasn’t really changed that much. It all boils down to getting the main content to your users as quickly as possible. Run through the test to see how your site performs, try to prioritize the fixes and get started! Below you’ll find a mix of old and new ways of enhancing your site to improve your Core Web Vitals.

Optimize your images

I’ll start off this list with a golden oldie: optimizing images. One of the most important things you can do for your site is properly optimize your images. Yes, we said that a million times but we’re going to say it again: do it. That one big unoptimized image on your homepage or landing page might hurt you. Large images are often the largest contentful paint (LCP) for any given site. Make sure you give your visitors a proper welcome by making that load quick!

We have a popular article on image SEO describing what you can do to get that image to load quickly. But in short, make sure you serve it in the size needed and compress it well. There are loads of tools to help you do this. Personally, I love the results I get with squoosh.app. Don’t think you need to keep that massive resolution for that image to be sharp on the most common screens.

Also try to adopt modern formats like WebP. These formats can deliver high quality images at a lower size. WebP is well-supported and even Apple has jumped on board! The upcoming Safari 14 release — both on MacOS as well as iOS — will support WebP. Yes, the new Chromium powered Microsoft Edge browser also supports WebP.

Your CMS is also a tool that’ll help you improve the loading images. Due in August, WordPress 5.5 will support lazy loading of images. This means it will only load those images that appear on screen and leaves the rest to load when the user interacts with that screen. This tells the browser to load large images only when they are needed.

Another piece of evergreen site speed advice is the use of a CDN, but did you know you can also use a CDN specifically for images? An image CDN gives you more control over how you want to serve and how you want these to appear. An image pushed by an image CDN gets a string of properties in its URL which tells the browser how the image should behave.

Stabilize loading by specifying room for images and the like

One of the new metrics is cumulative layout shift, or CLS for short. An example of this is when a mobile page looks ready and just when you want to hit a button, the content shifts and a slow loading ad appears in that place. This happens often and is one of the main causes of frustration for users. Now, while optimizing your CLS won’t necessarily make your page be faster it sure makes it feel faster.

CLS is caused by images without dimensions in the CSS. It can also be caused by ads and embeds without dimension, or dynamically injected content. When not properly given dimensions, these elements tend to jump just a bit during the loading process, making it appear jerky and unstable. This might also due to new content being inserted above existing content. Don’t do that, except maybe after an explicit interaction by the user.

One of the ways you can improve Core Web Vitals and prevent CLS is by adding the width and height for images in the CSS. This way, the browser will reserve space for that image that’ll probably appear later than the text. Now, the jerkiness will disappear because the browser knows that something will be added in due time. You could think about adding some sort of low-resolution placeholder if you want sometime to appear quickly.

So, simply make sure that your images have proper width and height attributes set. Of course, you can also do this with regular responsive images. Just make sure that you are using the same aspect ratio for all sizes.

<img src="mountain.jpg" width="640" height="360" alt="Mountain underneath a cloudy sky">

To cope with jumping ads or injected content, please reserve space for these as well. In the end, your CLS might just come down a bit.

Speed up your server to get that loading time down

The faster your server responds to requests, the better. Getting that server to respond quicker directly improves a lot of site speed metrics. On complex sites, the server keeps busy with handling requests and serving files and scripts, so it’s best to optimize those processes.

Optimizing your server consists of several parts. First, upgrade your hosting plan. Don’t skimp on hosting. Pick one that offers good performance at a fair price. Also, there’s the business of how the server was set up — use a recent version of PHP! — and what hardware you picked. Maybe you should upgrade the hardware if you find that lacking. Also, you need to research how your databases work and see if you can make improvements. Use tools like the Query Monitor WordPress plugin to keep analyze queries on your site.

You can also look into how your server pushes files to clients. There are several ways to enhance that process, with link rel=preload for instance, or HTTP/2 server push. These are more advanced solutions that let you fine-tune how your server responds to requests. Here, again, a CDN can do wonders to improve your Core Web Vitals.

Look into critical CSS to load above the fold content quicker

When the browser loads a page, it has to get the HTML, render it, get the CSS, render it, get the JavaScript, render it, et cetera, et cetera. The more files you need to load your site and the bigger these are, the slower your site will load. Often, while the browser is busy doing stuff, it can’t load things in the background. Certain elements block the process. So-called render-blocking JavaScript and CSS influences everything.

Since the CSS loads late, it can often take a while for something to appear on screen. By taking the critical bits of your design — the part that appears above the fold — out of the main CSS file and inlining it in your code, you can get something on screen much faster. Fixing this, once again, doesn’t make your site faster, but it makes it appear faster. All for that ace user experience.

To get a set of critical CSS, you can choose from a number of tools or you can do it by hand. In addition, you can use WordPress caching plugins like WP Rocket. WP Rocket has a simple button called Optimize CSS delivery. Activating this helps eliminate render-blocking CSS and enhance the loading of your site. Of course, WP Rocket also does other cool stuff like minifying CSS and JavaScript and deferring the loading of JavaScript.

Improve loading of third-party scripts

For many sites, slowness also comes from outside. If your site relies on ad scripts, for instance, you are basically in the hands of the ad provider. You can only hope that they make their ads performant. If their ads load really slow, well, maybe it’s time to find another provider.

If you find that third-party scripts slow down your site, you should look into this. Ask yourself, do I really need that particular ad? What’s the value of these scripts? There might be a different option out there that’s a bit more optimized and less stressful for your server. Maybe try that?

If possible, you can experiment with hosting the script yourself. This way, you’re a bit more in control of the loading proces. If you can’t do that, see if you can get it to preload quicker.

At the least, make sure to load the scripts asynchronously or defer it till the last moment. This way, the browser can build the page first before getting and running the external script. Use async if the script you’re loading is important, like an analytics script. You can use defer for less critical resources. There’s loads of documentation on optimizing third-party scripts.

Improve Core Web Vitals: All small improvements count

With the page experience update coming in May 2021, Google put site speed and user experience front and center again. We’ve always looked at SEO holistically — there are many moving parts and you should work on all of them to build the best site out there. Although the tips mentioned above can help you improve those Core Web Vitals scores, you really should be doing this to offer your visitors a better experience.

29 Responses to 5 ways to improve your Core Web vitals

  1. David
    David  • 6 months ago

    Thanks for the info

    • Camille Cunningham
      Camille Cunningham  • 6 months ago

      You’re welcome, David :)

  2. Rose Mave
    Rose Mave  • 6 months ago

    I’m actually looking for ideas and strategies. This is extremely helpful, Thank You.

    • Edwin Toonen

      You’re welcome, Rose.

  3. Jay
    Jay  • 6 months ago

    For a lot of people diving into server configs is quite a puzzle I find. Although it would be a good tip to check out the settings you can access through your Cpanel / DirectAdmin / Plesk. Although some hosting providers (at least in The Netherlands) simply do not allow you to tweak your own server settings (which should be reason enough for you to find a different hosting party). Also, don’t assume your hoster has set the optimum settings for your site, as they tend to generalize their settings to be “one size fits all”. Tweaking is necessary (and can break your site), but there are plenty of “best practice” guides out there.

    • Edwin Toonen

      Thanks for your tips, Jay!

  4. Edwin James Lynch
    Edwin James Lynch  • 6 months ago

    My scurity software saw Web.dev/measure as a Phishing site so maybe be careful with that one.

    • Edwin Toonen

      That’s strange, Edwin (great name, btw). Why would a Google site appear as a phishing site?

  5. Angie B.
    Angie B.  • 6 months ago

    Thanks for the great check list.
    Started to cross points off and already the query tips has proven to be very insightful.

    • Camille Cunningham
      Camille Cunningham  • 6 months ago

      You’re welcome, Angie. That’s wonderful to hear :)

  6. Jothybasu
    Jothybasu  • 6 months ago


    This article is really useful for beginners in Seo. I have a doubt, Does AMP pages will reduce the loading time of the website.

  7. SwiftChat Live Chat App
    SwiftChat Live Chat App  • 6 months ago

    Limiting and making sure that third party scripts load quickly is a great tip!

    • stefan van vliet
      stefan van vliet  • 6 months ago

      Hey girls/guys,
      If sitespeed is so important to SEO, and yoast claims to handle SEO from A to Z ( the S for sitespeeds is within that spectrum :) )
      Why isn’t yoast handling the sitespeed.
      Thus, there wil be no competition left when you would tackle that. Since the plugin is already great as it is now, it would tower above the rest handling sitespeed and user experience.

    • Sayem Ibn Kashem
      Sayem Ibn Kashem  • 6 months ago

      Great tips! You have cleared some of my confusions.

      • Camille Cunningham
        Camille Cunningham  • 6 months ago

        Thanks, and good luck in implementing our tips!

  8. Atul Host
    Atul Host  • 6 months ago

    The tool of wed.dev is not accurate or reliable to everyone because no matter where your website is hosted it will test the metrics for the USA only. So better use this tool only if your site is hosted in the USA.

    • Edwin Toonen

      Hi! Web.dev is powered by Lighthouse, which delivers both field and lab data based on which report you’re looking at. Field data is gathered from millions of users around the world and this gives great insights into real-world usage of pages. Of course, the results fluctuate as Google also states in their Scoring Guide: https://web.dev/performance-scoring/. This might be why you see different results.

  9. Pete
    Pete  • 6 months ago

    FYI you have the link as Web.de/measure

    but the link is actually Web.dev/measure

    in this paragraph.
    Many tools also give advice on how to fix stuff. Web.de/measure, for instance, doesn’t do in-depth results, but it does give you an idea of what the impact of a particular fix is.

    • Willemien Hallebeek
      Willemien Hallebeek  • 6 months ago

      Great addition, Pete! And thanks for letting us know, we’ve fixed the link.

      • Pete
        Pete  • 6 months ago

        You’re welcome Willemien, and thanks for the post.

  10. Walter
    Walter  • 6 months ago

    Seems like you have typo on web.de/measure instead of web.dev/measure. Still, I love your post about this anyway, short and simple, easy to understand.
    I faced some troubles in the past even after optimizing any other elements, nothing seemed to work out.
    But the only remaining problem there was the server load time, changed my shared hosting to VPS, it’s a lot faster now.

    • Willemien Hallebeek
      Willemien Hallebeek  • 6 months ago

      Great to hear you’ve found a solution, Walter! Thanks for sharing your experience and informing us about the link. Fixed it now :-)

  11. Kyle Hoffman
    Kyle Hoffman  • 6 months ago

    Nice blog post guys. Can confirm that switching hosting is one of the best things you can do to speed up your site. Switched from Host Gator to Site Ground and saw improvements immediately.

    • Willemien Hallebeek
      Willemien Hallebeek  • 6 months ago

      That’s great, Kyle. Thanks for sharing your experience and good for you your site got faster.

  12. 6VIDS
    6VIDS  • 6 months ago

    We managed to get everything on the green side on Lighthouse by moving as much as possible on a CDN, having scripts on the edge of the CDN as well.

    • Willemien Hallebeek
      Willemien Hallebeek  • 6 months ago

      Smart! Thanks for sharing this, 6VIDS.

      • Steffen / UV Leuchten
        Steffen / UV Leuchten  • 6 months ago

        Great information and ressources from Yoast. We´re also using your premium plugin and it is always great that we are uptodate with your newsletters and blogposts. In Addition to your great post about the web vitals I would recommend to check first the Google pagespeed insights metrics on the website (https://developers.google.com/speed/pagespeed/insights/) where most of the problems/recommendations are checked regarding this post. So I think in 2020 and the upcoming future, there websites that focus on a combination on Onpage UX and also technical aspects will outperforme the ones which don´t take these points into account.

        • Camille Cunningham
          Camille Cunningham  • 6 months ago

          Hi Steffen, thanks for your addition! Google PageSpeed Insights is definitely another great tool to test your site speed. In this article, we talk more about Insights and other similar tools and why they’re useful for different assessments: https://yoast.com/how-to-check-site-speed/