Could Removing Google Tag Manager 1.5x Your eCommerce Conversion rate?

Explore emerging Google Tag Manager alternatives that can help you achieve the same objective without the conversion rate setback.

Many of us have closed out of a website because it was taking too long to load. We inherently understand the consequences that a slow website can have on user retention and experience, but just how significant is speed’s impact on performance? Several studies conducted by industry-leading organizations justify the business case for web performance improvements:

  • In 2006, Amazon purposefully increased its site's load time and discovered that a mere 100ms speed decrease resulted in a 1% drop in revenue. 
  • For e-Commerce sites, those that load in 1 second have a conversion rate that is 1.5x higher than a site that takes 10 seconds to load (Portent).
  • Google and Deloitte found that reducing the load times for mobile sites by just one-tenth of a second could significantly enhance conversion rates. Specifically, conversion rates improved by 8.4% for retail and 10.1% for travel.

Interestingly, this effect isn’t exclusive to eCommerce conversion rates. It’s equally applicable to B2B sites - where a site that loads in 1 second boasts a conversion rate that’s 3x higher than a site taking 5 seconds to load.

But what if the tools designed to optimize your site are actually slowing it down? Google Tag Manager, a popular tool amongst marketers to simplify analytics and advertising workflows, has page speed implications. A study by Analyticsmania found that merely eight tags in Google Tag Manager could spike page load times by a shocking 70-80%. To put this into context, the median number of tags on a website is between 21-23.

So, could eliminating Google Tag Manager potentially be the key to eCommerce conversion optimization and a 1.5x boost in conversions? Page speed and conversion rate are closely connected, and this article dives deep into some emerging Google Tag Manager alternatives that can help you achieve the same objective without the conversion rate setback. 

The Origins of Tag Management 

Tag management's evolved from web analytics which began in the 1990s with Urchin Tracking Module (UTM) parameters, which initially served track user activity across the internet and offer insights into performance of various marketing campaigns. 

As the marketing landscape expanded, developers incorporated ‘pixels’ and then ‘tags’ (Javascript code) into pages to better track user activity.  With increasing data comes the need for analysis. In the late 00s, Google Analytics and Adobe Analytics emerged as the leading tools web performance analysis. 

However, managing these tags became complex and required developers to add ‘tags’ to websites. This gave rise to Tag Management Systems (TMS) such as Google Tag Manager. TMS enables marketers to inject tags without the need for developer assistance, which aids in streamlining marketing campaigns and data collection activities.

The tags loading on your site don't just slow down your webpage (due to the increased load to run and evaluate), they also enable the advertising providers who own the tags to collect data. With increasing privacy concerns and the need for faster page load times, server-side tagging solutions like Cloudflare Zaraz are beginning to appear. These solutions shift the tag execution from the user's browser to the server, enhancing user experience and providing better control over data privacy.

GTM CS vs GTM SS vs Zaraz

So, what options do you have? How can you speed up web page loading time? We have evaluated three of the leading tag solutions against four fundamental requirements. The options are:

  1. Google Tag Manager Client Side (GTM CS) - This is the most commonly used tag management system and presumably the default currently utilized by marketers
  2. Google Tag Manager Server Side (GTM SS) - Introduced by Google in recent years to help address privacy and page speed concerns 
  3. Zaraz - A new alternative to GTM SS provided by Cloudflare, a leading web solution provider  

The four key areas we use to evaluate these tools are: 

  1. Page Speed (and thus conversion rate) 
  2. Ease of use for marketers 
  3. Total Cost of Ownership
  4. Security & Privacy 

Page Speed - Winner: Zaraz

The critical battlefield of page speed sees Zaraz emerge victorious. 

The impact of third-party scripts on page speed hinges on how much of the process happens client-side (in the browser) vs. server-side. 

Breaking this into three core actions, we have:

  1. Events - such as clicks, page loads, or a user adding an item to their basket
  2. Triggers - custom logic dictating which events a tag should monitor 
  3. Tags - custom scripts that initiate when the tag’s trigger fires

Zaraz outperforms its competitors since it relies on the browser only to initiate events, while the evaluation of which triggers fire and the running of scripts are all handled server-side. In contrast, Google Tag Manager Server Side (GTM SS), still completes event and trigger evaluation client side, and Google Tag Manager Web (GTM CS), performs all three processes client side. 

It’s worth noting that GTM SS requires both server-side and client-side containers, and tags without a direct API, such as LinkedIn, continue to load and execute in the GTM CS container. Zaraz manages all of this outside of the browser and merely passes the browser an HTTP request to send to LinkedIn. This gives the benefit of a client side tag without having to load it on the page. 

The 1.5x increase in conversion rate is predicated on Zaraz vs. a full GTM CS implementation. However, when you break this down into its component parts you can estimate the performance improvement vs. GTM SS:

  1. Not executing tags on the client side (estimated to account for ~70% of the performance improvement) 
  2. Not evaluating triggers on the client side (estimated to account for ~30% of the performance improvement)

Whilst these numbers are estimates, the relative performance of Zaraz vs. GTM SS will likely depend on the number of tags you use that don’t have an API (e.g. LinkedIn) and the number of triggers you have in your GTM container. 

Ease of Use for Marketers - Winner: GTM

In terms of user-friendly interfaces for marketers, GTM CS prevails. 

Both Zaraz and GTM offer similar user interfaces, but GTM has a more advanced open-source component library and supporting documentation. Both GTM CS and GTM SS benefit from influencers, such as Simo Ahava, publishing comprehensive ‘How to’ guides and other unofficial documentation.  

GTM SS adds minor complications since it requires technical set up, but once this is complete, it shares the same UI as GTM CS. 

Zaraz offers handy shortcuts, such as setting tool configurations per destination. For example once you have set your Google Analytics Configuration, this applies to all Google Analytics 4 (GA4) tags. In GTM, however, you need to establish this for every tag. However, Zaraz requires more technical resources to create new destinations when things aren't already set up.

Total Cost of Ownership - Winner: GTM CS

When considering the total cost of ownership, it’s crucial to consider both set up costs and ongoing maintenance costs. Assuming that you have GTM CS set up already, this will likely be the most cost-effective as it is free to use and requires no additional setup. However, it is important to consider this in light of the potential conversion rate increases you could gain from switching to GTM SS or Zaraz. 

Comparing the other two: GTM SS involves maintaining a separate server, which incurs ongoing costs not only from paying for the server but also from its maintenance. It benefits from leveraging your existing GTM CS set up, thus additional setup will be minimal (assuming you already capture all the data you require in GTM CS). 

Zaraz, on the other hand, operates on a usage-based pricing model which, while more expensive, incurs lower technical maintenance costs vs GTM SS in the long run. It’s part of Cloudflare, so it’s straightforward to set up if you’re already using Cloudflare. It also offers a useful ‘dataLayer’ compatibility feature where you can use your existing GTM CS dataLayer events in Zaraz. However, it is crucial to note that eCommerce companies would need to reconfigure their eCommerce data layer events for compatibility with Zaraz.

Privacy and Security - Winner: Zaraz 

When it comes to privacy and security, Zaraz provides superior control and visibility over third-party tools. 

With GTM CS, third-party scripts are loaded onto the page, and it's unclear what data they collect. Both Zaraz and GTM SS can limit this data collection by introducing an intermediary container before sending to third parties.

It’s important to note that Zaraz evaluates all operations server-side, even replicating network requests for destinations like LinkedIn that must be client-side in GTM SS. 

Zaraz also includes additional privacy features in its tooling that allow marketers to meet an interpreetation of GDPR requested by French regulator CNIL, including IP hiding.


In conclusion, website speed significantly impacts conversion rates and revenue. While Google Tag Manager (GTM) is a popular tool, it can contribute to slower site speeds. Alternatives like Zaraz offer server-side execution, improving page load times and potentially boosting conversion rates. However, GTM continues to excel in terms of ease of use for marketers and cost-effectiveness. For privacy and security, Zaraz provides enhanced control and compliance features. 

Considering the importance of site speed, it may be worth exploring alternatives like Zaraz for businesses seeking improved website performance and better business outcomes.

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