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  • Writer's pictureRick Kenney

The Impact of 3rd Party Technologies on Site Speed

Site speed and performance is the commerce bridesmaid. Often considered, but frequently losing out at the alter to a shiny new 3rd party technology with promising returns. Ironically, that same 3rd party that wins out, is typically a performance hog, contributing more drag on page load, and harming the very performance initiative that it helped de-prioritize.

In the Site Speed Standard, we see the impact that speed has on shoppers. Slow sites sap conversion. The tl;dr on speed according to that benchmark:

  • Save One Second: When you save 1 second per page load, mobile conversion rises 5.7%.

  • Beat 4 seconds: Nearly 60% of conversions happen on sites that beat 4 seconds (per page load) and ~60% of bounces happen on sites that trail 4 seconds.

Just as the Site Speed Standard helps you know ‘how am I doing’ the eCommerce Technology Index analyzes the performance impact of more than 500 popular 3rd party technologies installed across more than 1,500 eCommerce sites to help brands and retailers know the real performance impact of one of the main sources of site performance issues: 3rd party technologies.

Know Your Stack

eCommerce wouldn't be what it is without the generous use of 3rd party technologies. Brands and retailers apply innovative tech across the entire shopper journey to drive traffic, optimize conversion, and improve customer service. All that tech has an impact on how a site performs. Bluntly, unfettered tech is going to slow your site down. And, slow sites stop conversion.

So, how should we measure the performance impact of a 3rd party technology? Start by looking at the primary issues a 3rd party can cause: page delay and performance risk.

  • Page delay extends the amount of time a page takes to load. Longer page load hurts conversion by increasing bounces and forcing shopper to wait.

  • Performance risk occurs when a 3rd party takes too long to load, potentially rendering it's functionality inaccessible.

Combining the rate of these occurrences provides a true indicator of a 3rd party’s performance impact. This value, Performance Impact Rating, or PIR, is a must-know metric for brands and retailers assessing their ecommerce technology stack. PIR is also the foundation of the eCommerce Technology Index.

The eCommerce Technology Index covers a wide assortment of performance metrics - concentrating on the impact of 3rd parties across a number of site performance measures. Here are three of the top insights from across the Index:

Category Performance Varies

When shopping for (or simply assessing your current) technology, understanding how a specific category of technology may impact your site is important. We measured the ‘positivity’ of each technology category to see which categories are generally more or less impactful to performance. Beware of these categories - Personalization, Tag Management, and Chat - which are most likely to have a significant negative impact on site performance.

Page Delay Demons

The typical promise of adding a third party is for growth - to boost conversion or indirectly, to gather data useful for driving traffic or making decisions. Those gains do come at a cost, and sites feel this most acutely when a tech delays page load. Retailers that don’t address site performance incur all that cost, by way of 27% slower page load times.

Here’s a view into how each category impacts page load, including those page delay demons that add significant tie to a page load, like tag management and customer reviews.

Page by Page

Across the shopper journey, each page serves a slightly different purpose, and thus holds a different performance impact footprint. The home page is a brand institution, the flag bearing representative of a site. It is also the most offending of all pages, as measured by the rate of performance and page delay violations. The most trafficked pages, the product detail page and category page are not far behind. Known for carrying a lot of conversion-boosting technologies, both page types throw off violations at a high rate.

However, while home pages are generally visited once during a session, the PDP and Category pages consume multiple page views as a shopper works through the journey - multiplying the negative impact that a shopper feels across their journey.


Knowing the impact that your current - and future - tech has on your site and your shoppers is likely to increase your appetite for site speed and performance optimization. Get to know the impact of your tech stack at the eCommerce Technology Index.

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