How Google Tag Manager and Overzealous Data Collection Can Hurt Site Performance

Using third-party tools like Google Tag Manager are a blessing for marketers and brands who seek to track web activity. But our overzealous data collection habits may actually work against the very performance we work so hard to measure and manipulate.
by 
Brian Beaupied

As marketers, we have an insatiable appetite for data. We use customer information to anticipate needs, understand our own effectiveness, and guide decision-making. When it comes to analytics and other third-party measurement tools, we simply can’t consume enough.

But all this binging can leave our sites and applications bloated. Our overzealous data collection habits may actually work against the very performance we work so hard to measure and manipulate.

Take Google Tag Manager (GTM), for example. This simple and powerful tool allows marketers to track an almost endless amount of activity across websites and applications through tags that can be created and deployed without a developer. It allows marketers to add third-party tools and the code that comes with them to their sites quickly and easily.

For each tag and tool we add to our site, though, this adds additional code. Whenever we add complexity, the potential exists to slow page loads and site performance. This drop in performance can cause users to bounce, working against the very behavior and results we’re hoping to measure and improve.

You can get a readout of your site performance using yet another Google tool, PageSpeed Insights, and receive suggestions on where you can improve. It offers data points including time to interactive, first contentful paint, and more on a 1-100 grading scale. While many teams end up becoming fixated on this PageSpeed Insights score, know that GTM is just one of many influencers of site performance. You can balance tag usage and performance to get the tracking you need without sacrificing performance.

This was the case with an ecommerce client of ours and work we’ve done to help optimize site performance. While front- and back-end optimizations drove a 50-point improvement in the client’s PageSpeed Insights score, the team also identified that turning off GTM could boost this score by another 10 points. This, however, would come at the expense of tracking potentially critical interactions and conversion points.

Here’s the advice we give to clients on how to best balance GTM and tag usage with overall performance:

Don’t overdo it: It’s easy to get caught up in all the possibilities for tracking events and interactions that GTM offers. But tracking every click, scroll, and interaction can cause your page load times to suffer. We recommend identifying and tracking only the most important interactions and conversion points for your business.

Review regularly: As with all tools, there is a certain amount of hygiene required with GTM as you go. Campaigns and important interactions and conversion points are likely going to change over time, so allocating time to go back and clean up unnecessary or pause any unused tags will help stay on top of page performance. Another step you can take is to make sure tags are only firing on the pages where they’re needed, or looking at delayed tags based on time or scroll to not impede with the initial page load.

Don’t chase perfection: Pursuing a score of 100 isn’t the right intent when using PageSpeed Insights. Instead, focus on the recommendations and making incremental progress to improve site performance. Increasing your score and performance is going to improve the user experience, even if it doesn’t net you a perfect score.

Remember, there’s a balance between the tools and tags we use for data collection and the performance of the sites and applications we’re monitoring. By focusing on what’s truly important for our organizations and committing a little time for cleanup, we can improve our GTM practices and usage without sacrificing performance. Meanwhile, use a tool like PageSpeed Insights to get other ideas on how you can help give site performance a boost!

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