11. January 2022

Pagespeed & Webtracking

Everything you need to know.


A special thank you to Johannes Fröhlich and the Digital Marketing Agency Dreifive for the mutual assistance for the blog article. 

Since June 2021, Pagespeed has become a crucial ranking factor with the integration of the Core Web Vitals into the Google algorithm. It can be decisive when it comes to displaying your website as high as possible in the search engine.

Google even goes a step further and says: the faster your website, the more conversions. Hmm… 

But imagine the following: You’re standing in the middle of your favorite city and decide to look for a burger joint because you just met up with an old friend. You have the latest iPhone with perfect 5G connection. 

The hunger is great. 

The competition is greater – a burger joint on every corner. 

The distraction is the biggest – the friend is already chatting with you cheerfully, the traffic around you is noisy….

Now every second counts and page load time can actually be the decisive conversion bringer for the burger joint. 

But even with a bad smartphone and an even worse internet connection, the desired information should be found quickly – that’s Google’s goal. 

So yes… page load time can be crucial when it comes to whether customers find YOUR brand, trust YOUR business, and ultimately buy from YOU. 

No matter what you prioritize in 2022 – revenue growth, customer retention, or scaling internationally – it all depends on the performance of YOUR website. 

But where are the biggest levers when it comes to pagespeed optimization? And how can server-side tracking, and specifically JENTIS, help? You can find out all about this in this blog post. 

But first, for a better understanding, here’s a brief explanation of the Core Web Vitals:

Enlightened: The Core Web Vitals in a nutshell

The Core Web Vitals are THE new core metrics from Google, which together with other metrics result in the ranking factor “Page Experience”:

The Core Web Vitals consisted of three KPIs for evaluating the usability of websites: 

  • Speed: Largest Contentful Paint (LCP) 
  • Interactivity: First Input Delay (FID)
  • Stability: Cumulative Layout Shift (CLS)


Important: Google will adjust the Core Web Vitals to the technical requirements as well as the user behavior and evaluates them regularly. Adjustments of the metrics are therefore not excluded.

Let’s take a brief look at the key metrics below:

Largest Contentful Paint: How fast does the website load?

In a nutshell: The Largest Contentful Paint (LCP) measures the loading time that passes until the largest content element (images, videos, text blocks) in the visible area of your website is loaded. 

Google defines the following values: 

  • good: up to 2,5 seconds
  • needs improvement: 2,5 – 4 seconds
  • bad: 4+ seconds

The loading status determines which is the largest content element of your website. The largest element is usually loaded at the end. The following is an example of our JENTIS website:

You can find all the details and the exact calculation basis of the LCP here in the Google documentation on Largest Contentful Paint

First Input Delay: When can the user interact with the website?

In a nutshell: First Input Delay (FID) measures the amount of time that elapses between the first user interaction with the website and the browser response. 

When you visit a website, you may click a button without waiting for the website to fully load. However, the browser usually does not react at that time because it is busy loading the website. To prevent users from jumping off now, the FID measures how much delay passes between the user input and the browser’s response. The main factor for the calculation is the “Time to Interactive”.

Google defines the following values:

  • good: up to 100ms
  • needs improvement: 100-300ms
  • bad: 300 ms or more

You can find all details about the FID here in the Google documentation about the First Input Delay.

Cumulative Layout Shift: How stable is the website?

In a nutshell: The Cumulative Layout Shift (CLS) indicates whether and to what extent unexpected layout changes occur while the user interacts with your website.

Unexpected layout changes happen when layout shifts occur as the site loads, and elements slide down as other elements are reloaded. This can have undesirable consequences for the user.

Google defines the following values:

  • good: 0.1 
  • needs improvement: 0.1-0.25
  • bad: 0.25 or more

All details and the exact calculation basis of the CLS can be found here in the  
Google documentation on the Cumulative Layout Shift.

So much for the definition of the Core Web Vitals (LCP, FID, CLS). 

Now let’s go into practice:

How to retrieve the Core Web Vitals

You can check how well your website is performing either via Google Lighthouse, the Google Search Console or directly in Google PageSpeed Insights. Simply enter your domain in the input field and click on “analyze”.

After a few seconds you will receive information on whether your website has passed the evaluation according to the Core Web Vitals – or not. 

You also get a speed score for mobile and a speed score for desktop. This score is between 0 and 100, where 90-100 is good, 50-80 needs improvement  and below 49 is bad

Tip: Since March 2021, Google indexes only “mobile first”, it is important that your speed score fits mobile. As a result, it usually automatically fits for desktop as well.


The result of the Core Web Vitals is provided as field data and lab data. Field data is anonymous data of real users on different devices and with different connection speeds. Lab data is simulated data on a single device and with a fixed network connection. 

Depending on the results, you will receive a set of recommendations from Google that can be used to reduce the loading time of your website, as well as a prediction of how many seconds it can be reduced by: 

What are the biggest optimization levers?

Every single recommendation from Google is a good optimization lever. 

However, you have to put costs and benefits in perspective (as always). Google still values good content the most. So before you invest tens of hours to make your website 100 ms faster, it probably makes more sense to invest this time in good, user-friendly content.  

In the following, however, we would like to show how server-side tracking and JENTIS in particular can support PageSpeed optimization. In doing so, we will directly follow the recommendations from Google’s PageSpeed Insights: 

Pagespeed Optimization with JENTIS

JENTIS is an innovative, powerful and compliant server-side tracking solution. 

 You can read about the benefits of server-side tracking and how server-side tracking compares to client-side tracking in this blog article:
Paradigm Shift in Web Tracking. Why your standard solution is at a dead end and how you can overcome these challenges with JENTIS.


Some benefits of server-side tracking even have a direct impact on faster page load times. Let’s start with the biggest optimization lever:

Eliminate resources that block rendering.

Did you know that 40% of the total Lighthouse score falls on running Javascript efficiently? 

So clean code accounts for a considerable portion of Google rankings.

To optimize Core Web Vitals, Google often recommends eliminating resources that block rendering: 

By “resources” Google mainly means Javascript, because the problem is that the more Javascript is loaded into the client’s browser, the larger the source code becomes and the longer it takes to download, parse and execute (render) the code. 

The cause of too much javascript is often in web analytics. 


The classic setup – an example: your website uses Google Tag Manager (GTM) and within it several tags for tracking and marketing. 

Let’s stay with tracking first: for Google Analytics you track not only the pageview but 25+ other events like newsletter signup, clicks on banners, etc. If you run an online store, you might want to add Enhanced Ecommerce Tracking. 

This is an e-x-t-r-e-m-e amount of javascript!

Of course the GTM loads the tags asynchronously and therefore parallel to the actually much more important content. However, the amount that needs to be loaded remains the same. 

Additionally, there is a lot of effort in the client’s browser, because the Google Tag Manager basically loads ALL code into the browser – which has to process the requests first. 

This takes time. 

In addition, the performance issues scale with the growth of your website. The more tags are configured in the GTM, the more Javascript is executed, the slower the website becomes – and according to Google, this has an impact on the FCP and LCP, i.e. the website speed. 

The following graphic should clarify the problem: 

How JENTIS helps

JENTIS provides its own tag manager – the JENTIS Tag Manager (JTM) – with the advantage that it ONLY performs basic communication in the client’s browser – asynchronously, of course. 

I.e. JENTIS also loads Javascript. However, the code is more compact and efficient than that of potential competitors – a decisive advantage, because the size of the code is indeed a non-negligible factor. 

ALL other tags are executed on the server side and thus do NOT load in the client’s browser – and the less code has to be executed on the client side, the faster the website, and so the better the loading time. 

The goal of JENTIS is to really only execute necessary Javascript in the client’s browser, as this ensures the fastest possible website load time. 

If a client-side execution is necessary, e.g. scroll tracking, JENTIS waits until all tracking codes of a page have been executed and sends them together to the JENTIS Tag Manager (datalayer push).

Reduce unused Javascript

Javascript is such a big optimization lever that Google lists a second item in PageSpeed Insights and for optimizing Core Web Vitals: 

Thus, unused Javascript should be reduced or at least only loaded when it is actually needed to reduce data consumption through network activity. This has a direct influence on the LCP, i.e. the website speed.

Here, too, web analytics has its finger in the pie, since countless 3rd-party tracking tags are often loaded into users’ browsers. So, for example, besides conversion tracking for your 5+ social networks, you also have a heatmap tool like Hotjar, an A/B testing tool like Optimizely, AWIN for affiliate, (…) configured. 

Of course, this is okay, as these are mandatory for efficient marketing, but the order in which Javascript is executed plays a significant role. Namely, all essential resources (images, videos, text blocks) should be loaded first. After that, any tracking. 

However, the order in which the tags are triggered cannot be regulated via the Google Tag Manager. They are executed asynchronously and thus in parallel – this is good, but whether images and texts are loaded before the Facebook pixel is no guarantee. 

This is where JENTIS comes in: 

Here’s how JENTIS helps

With JENTIS Tracking, instead of loading multiple 3rd party libraries, only one Javascript library is loaded – the one from JENTIS. 

This automatically eliminates the need for all 3rd party libraries. The order of the tags to be executed is therefore no longer important, because the execution is done later on the server side. The website is automatically faster. 

Depending on whether Hybrid Tracking or Backend Tracking is then used, the 2nd stream can also be saved. 

The JENTIS loading process is shown as follows: 

The loading process explained briefly: The desired tracking and marketing tags are configured via the JENTIS Tag Manager. The JENTIS Tag Manager generates a Javascript file for your configuration, minifies it and loads it onto the website. This means that only one file needs to be executed in the client’s browser, which significantly reduces not only the actual but also the perceived website loading time. In hybrid tracking, the server now generates the client stream and it is decided whether the entire JENTIS library or only a part of it is needed. Since the entire library is usually never required, fewer resources are needed and the loading time is reduced even further. 

A positive side effect of JENTIS: significantly higher data quality! Another advantage of fast-loading code on the client side is that data discrepancies between actual and tracked visitor numbers and sales can be reduced. Keyword: ad-blocker and tracking prevention methods (IT/ETP/TP)

This means that the marketing team has a much more reliable overview of user behavior and conversions. This in turn simplifies budget control and delivers even more effective campaigns.

But Google demands even more:

Minimize Javascript

Third-party codes actually affect the landing speed of websites tremendously. Google further recommends in PageSpeed Insights: 

Redundant third-party tags? 

You probably have them too. 

For example, you use Google Ads and Facebook and want to record your sales as conversions. To do this, you configure a Google Ads conversion tag and a Facebook conversion tag – in other words, two tags that track the same thing, namely the sale, the transaction. 

From Google’s point of view: double tracking. 

From the client’s browser perspective: bloated Javascript and thus unnecessary ballast. 

In addition, traditional client-side tracking will again load the library from the vendor, which in turn uses the CPU and RAM from the visitor’s computer to generate streams that are sent over the visitor’s network.

How does it work better? The conversion – the sale – is captured once and sent to the respective tools. This reduces javascript – and the less code that needs to be executed on the client side, the faster the website, and so the better the load time. 

It is precisely this tracking efficiency that JENTIS takes care of:

Here’s how JENTIS helps

Tracking takes place once with JENTIS and is forwarded to the respective tools on the server side. This significantly reduces Javascript AND saves the execution of 3rd party libraries. 

In addition, JENTIS compresses all javascript to be executed. 

The goal: to reduce the size of the source code even further, so that the transfer of data is even faster and more efficient. 

The following graphic shows how this works:

Numbers, data, facts

In numbers, this means that thanks to the compact and efficient JENTIS tracking code, the asynchronous loading of the JENTIS Tag Manager, the loading of only a single Javascript library and the efficient server-side tracking, JENTIS can reduce the loading time of the website by 604kb and thus, depending on the Internet connection, by up to 82 (!) seconds. 

82 seconds? 

Not in all cases. It depends on the Internet connection: 

  • 2G GPRS with max. 56kBit/s bandwidth: 82 seconds
  • 2G EDGE with max. 220kBit/s bandwidth: 22 seconds
  • 3G EDGE, UMTS: up to 13 seconds
  • 3G HSDPA: 0.7 seconds
  • 4G LTE: 0.24 seconds

The following graphic gives a better overview again: 

So even in 4G, JENTIS can be the icing on the cake, because every improved millisecond has a positive impact on conversion rates and customer satisfaction, and thus on Google rankings. 

How are the 604kb calculated? 

We tested this with our customers. 

In this case, with a large online store that is mainly active in the D-A-CH region and has switched from Google Tag Manager to JENTIS. For a while, both tracking systems were running in parallel and we took this as an opportunity for our testing.

In total, the GTM accounted for 365kb. Additional third party scripts added another 281kb to the user’s browser load. TOTAL: 646kb

In comparison, the JENTIS library loads at 42kb. This makes an advantage of 604kb over the Google solution. 

You can see the details in the following graphic:

Conclusion: Optimize pagespeed with JENTIS and profit.

With the Core Web Vitals, Google has given webmasters, web developers and SEOs three KPIs that have several advantages: They are clearly communicated, apply to everyone in the same way and can therefore can be optimized in a targeted and comprehensible way. SEO is thus no longer a black box. 

An excellent Speed Score is therefore relevant for ALL websites – for highly competitive companies it is even fundamentally important, as a fast loading time leads to an even better user experience and thus to more conversions.

However, costs and benefits must ALWAYS be put into perspective. With JENTIS, and thus with a performance-oriented and at the same time powerful server-side tracking solution, you can reduce your Pagespeed by up to 82 (!) seconds. 

It’s the greatest possible leverage with comparatively low resource requirements and at the same time manageable costs, because you can start using JENTIS today for as little as €500 per month. 

Note: Pricing is based on the number of events you need for your tracking plus the number of pixels implemented through JENTIS. Find the right plan for you here.


Ready to speed up your website and boost sales? Let’s talk