Blog Post

The Effect of Third Party Tags on Website Performance

To understand the actual impact of third party tags, we have run a series of performance tests on the most visited sites.

Marketing technologies are exploding across the web.

Digital marketers are harnessing emerging analytics, tracking, social, and advertising platforms to calibrate their 1:1 marketing efforts and maximize ad revenue. To deliver the level of personalization that customers have come to expect, a brand might easily use 20 or more web-based marketing technologies.

Sadly for IT/Operations, most applications must be added to the website using snippets of code called third party tags, which can slow down pages and leave sites vulnerable to failure if not managed properly.

Many of these tags are legitimate, necessary components to your overall online strategy and provide a variety of different business advantages. Given the Catchpoint co-founders’ experience at Google and DoubleClick, the importance of third party services is certainly not lost on us. Yet it’s also true to say that every single third party provides a potential roadblock towards performance, and some of them are better than others at seamlessly integrating their content into the sites on which they’re hosted.

To understand the actual impact third parties have on some of today’s biggest websites, we ran a series of performance tests on the most visited sites from the banking, eCommerce, news, and travel industries.

Testing methodology

We selected the ten most visited sites according to the following indexes: banking, eCommerce, news, and travel. We grouped first party elements (served from internal hosts and CDNs) and third party elements (containing the aforementioned technologies) from the homepage into two zones and ran performance tests from 12 US Catchpoint Synthetic nodes for the past week. For each of these sites, we took the median metric from all the tests, and then compiled a mean average among those medians to get the industry average.

The Results

Third parties can weigh down your site

3rd parties downloaded bytes
Downloaded Bytes the total size of the data downloaded from the page, including page HTML

The graph above shows that tracking tags are most prevalent on news sites, making up nearly two-thirds of the total downloaded bytes for news sites – which regularly report longer wait times than the other industries tested – and over a quarter of those for travel sites. The percentages are significantly lower for banking and eCommerce sites, but still represent a sizable portion of the data that they deliver to their users.

Third parties can slow down your site

3rd parties speed impact bottleneck time
Webpage Load Time the time it took from the request being issued until the onload event fires

Third Party Bottleneck Time the amount of load time taken up by presence of third party tags

In these two graphs, the impact from the third party tags becomes clearer. As expected due to their prevalence on news pages, those sites show the greatest speed impact due to third parties, as their presence constitutes nearly half of the total load time. Somewhat surprising is the higher percentage of bottleneck time that the eCommerce sites see from third parties (26.5%) compared to the amount of data on the pages that those third parties comprise (15%), as seen on the previous chart. This suggests that eCommerce sites have lighter tags on their pages, but are not as proficient as others when it comes to minimizing their impact.

A high average bottleneck time means a delay in loading a third party typically has a larger impact on the page’s total load time. Worse yet, if a tag times out, it could cause considerable delays.

When your page slows, users leave. And when users leave, you lose revenue.

Third parties can fail – and cause your site to fail

Unfortunately for websites and their end users, a large number of third party providers rely on inline JavaScript that is blocking (SPOFs). As a result, when these vendors have performance problems or downtime, the end users of their clients can also experience problems. And even if the error does not impact the end users’ experience, it could still have an impact on your business initiatives in the form of lost data or ad revenue.

When tags fail…

Problems created by third party failure can result in website unavailability or loss of functionality, and users associate the problem with the website and the brand – not with the third party that actually caused it. Because popular technologies can be used by thousands (sometimes millions) of sites, a single provider failure can cause a widespread outage.

Two out of every three of the top news and travel sites we tested had a Facebook Connect tag. So when Facebook went down last year, it’s no surprise that a large number of sites were negatively affected (talk to some unhappy music listeners who couldn’t log in to Spotify). When DoubleClick experienced an outage last year, several major sites slowed to a crawl and ad revenue took a plunge.

The lesson to take away is that whether you’re an eCommerce site, a content publisher, or any other kind of site, it’s important to have a third party certification process in place that sets minimum requirements for anyone to host a tag on your site.

So how to IT/Operations teams handle all these problematic tags without sacrificing their site’s overall performance? Check back tomorrow to find out.

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