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Keep Calm and Track On: Why Heap's Script Won't Slow Down Your Site

Anyone who uses the internet has seen bad site performance. Whether it’s a page that flickers from lagging A/B tests or one that takes forever to load in the first place, it’s an easy way to ensure that new visitors to your site don’t come back.

So it’s a good idea to do your due diligence when installing new scripts on your site to make sure the elements you’re adding will play well with everything else. The good news is that Heap’s autocapture tracking script won’t slow down your site.

Read on for details.

Why install the Heap script?

First things first: why should you even install the Heap script? Because that single snippet collects all behavioral data automatically (and retroactively!) from the moment it’s inserted into your site header. This means you can go back in time and analyze insights from past customer events that you weren’t even thinking about before. 

Heap’s small but mighty script puts all event activity at your fingertips — every click, swipe, form fill, pageview, and more. No need to decide in advance what to track. No need for engineers to instrument each behavior you want to analyze.

With other tools, answering your questions can take months. With all of your data captured automatically, you can ask anything because you have everything.

Plus, autocapture allows the data to speak for itself. That way, you’re able to keep yourself open to learning new things, and seeing them before other people can. A full data set provides complete and predictive insight.

Capture everything without slowing down anything

But wait, won’t collecting all of that behavioral data affect your website’s performance? The short answer: nope! The longer answer: still nope!

Heap’s script is loaded asynchronously, so heap.js won’t impact initial page load times. With asynchronous loading, your site can render multiple elements at the same time, instead of stopping to load each time it encounters another script.

Once the page is loaded, Heap minimally impacts page performance since it never touches the UI. That means it never triggers a re-render. Plus, Heap never makes any blocking network requests, and the network requests that it does make will never exceed 4kb.

Google Analytics’ script — which is installed on half the web — works the same way, without any impact on load time. At only a quarter of the size (less than 50kb) of GA’s script, Heap’s script is hosted on Amazon AWS Cloudfront, a global CDN, which allows for extremely fast load times.

Finally, none of our customers have experienced site performance impact from installing Heap’s code snippet. Instead, they got all of their users’ behavioral data captured automatically without having to tag every event.


Heap’s script won’t slow down your website. Capturing all event activity without degrading performance is as simple as inserting a single line of code into your site header. It won’t slow down your site, but it will speed up your team.

Have more questions? Reach out to our team via

Want to try out Heap’s script for yourself?

Installing Heap is simple. All you need to do is insert a single code snippet into your site header. Then sit back and watch the data roll in.

Give our script a spin on your site to see how easily you can get started analyzing your customer data. Start your free trial here with Heap today!