Improving Website Page Speed With The Help of Google Tag Manager Server-Side Tracking

When the first version of Google Tag Manager was released, one of the essential benefits that marketer and web developers saw is website page speed optimisation. It supposed to happen because tracking scripts would no longer be hardcoded, but would be added through Google Tag Manager. But is it true? Does GTM web container speed up your site?

In this article, we want to check how moving from Google Tag Manager Web Container to Server container can speed up your website.

Why Does Site Speed Matter?

According to Google research, if a site takes longer than 3 seconds to load, 53% of users will leave. At the same time, on average, it takes 22 seconds to load the mobile page fully. 

We live in a time when people use watch phones more then desktop devices, more than 50% of all Internet traffic falls on smartphones. But according to Google, conversion rate on mobile phones is lower than on the desktop. Website loading speed plays the essential role in this indicator.

It’s no secret that users expect a fast site experience. If a landing page is too slow, they’ll close the page or abandoned cart and move on to the competitors site. Today, in the mobile-first world, it’s critical to create fast sites. Users want to have the ability to quickly open your blog and read the article, or buy new clothes, check reviews of the hotel, etc. 

According to Amazon’s research, a one-second decrease in website load speed results in a 1% loss in conversions, which is equivalent to a loss of $1.6 billion in annual revenues for them.

As you can see, waiting for heavy pages to load can cost a lot for any company.

How Can Google Tag Manager Server-Side Tagging Speed Up Your Website?

In 2020, Google released a server container for Google Tag Manager and Tag Manager 360. Advertisers can move third-party tags from their sites to a new server container that is hosted in the сloud servers. This will make their site load faster, tracking more accurate, and data safer. Moving tags to the server container will help you to solve this Google Pagespeed error – “Reduce the impact of third-party code Third-party code blocked the main thread for”

Improving Website Page Speed With The Help of Google Tag Manager Server-Side Tracking heavy 3rd party code

If you move tags from web to server container, tags will be loaded directly in the server container, not inside user’s browser. Thus, the page will load faster; it will have a positive effect on the user’s experience. This provides faster page load times, more security for your customers’ data, and more data management tools.

Tags in the server container only have access to information sent to the server. They do not have access to other information that users enter on the site. And since these tags are placed in your server container, you can understand what data tags are collecting and where that information is sent.

What Is The Difference In Page Speed When Tags Are Placed Inside GTM Web Container vs Server-Side?

To do this experiment, I used a demo website and compared Google page speed results when tags were added via GTM web container vs GTM server container. Not all tags have the same impact on the Google page speed. While doing this experiment, I decided to choose the most popular tags that are used by my clients and those tags that are possible to move to the server container: Universal Analytics, Facebook, Bing and Active Campaign. 

GTM server container has native tags/clients for Universal Analytics and GA4. Here you can find detailed information on how to add Universal Analytics via your GTM server container. We also created a custom template that can help you move Facebook pixel to the server environment

These were the results of Google Speed test when all tags were added via GTM server container.  Google page speed showed 97 points on mobile and 100 on the desktop. 

Improving Website Page Speed With The Help of Google Tag Manager Server-Side Tracking server container

When we moved pixels to the web container, Google page speed results decreased to 86 points. If you use multiple Google analytics or Facebook pixels, the impact on the page speed results will be more significant. 

Improving Website Page Speed With The Help of Google Tag Manager Server-Side Tracking Web Container

Conclusion: If you move tags to Google Tag Manager server container, it will speed up your site. How significant this impact will be depends on tags that you are using. In this test, I tried to use the most popular tags: Universal Analytics, GA4, Facebook, Bing and  Active campaign. For now not all pixels can be set up via server container. For example, Twitter and Linkedin do not support server-side tracking (hope they will in the future). Tools like Hotjar are not compatible with the server-side tagging by default.

If you have any questions about server-side tagging, feel free to contact us via You can also test the GTM server container for free using our service, no credit card required. (Google will charge you $120/month minimum)