Ten things every marketer should know about web performance no. 5: third-party content can slow you down

Marketing and ecommerce departments have to make money. And there are a host of services and third-party add-ons for websites to help make that happen.

Remarketing services, for example, track individual visitors with a view to showing them carefully targeted ads on selected websites. Sophisticated multivariate testing solutions aim to pinpoint the optimum content and design to maximise revenue. The list of services goes on, and in recent years there has been an explosion in the number of companies offering them.

The impact on speed

What’s not always clear is that third-party services can slow web pages down. And that’s bad news for conversions and revenue.

This can happen for a number of reasons.

Many third parties require site owners to embed code (or tags) into the website. Sometimes, these are loaded synchronously. This means they block subsequent content on the page until they’ve finished loading, potentially delaying the display of the page. And if the file fails to load altogether (or is just very slow), the whole web page fails too, leaving visitors staring at a blank screen. This is the dreaded third-party single point of failure or SPOF.

The good news is that many third-party service providers have got much better at following best practices, such as offering asynchronous implementations. However, they can still affect the user experience. For example, they may take priority over first-party content as the page loads, or make it harder for the user to interact with the page.

What’s more, some testing services have to be loaded synchronously because they determine what the page will look like on any given visit (and we’ve already seen how an A/B testing service was responsible for slowing down a major retail site). 

Tag managers to the rescue?

One partial solution to the proliferation of third-party services was the tag manager. Tag managers offer simple interfaces and easy ways determine which tags should fire on which pages (and when). In theory, they help to minimise the negative impact of third-party tags.

However, they’ve also made it very easy to add those tags. The result is that tag managers have largely taken the process of embedding tags out of the hands of IT and placed it firmly within the domain of marketing (or agencies). Ironically, these solutions have made the process so easy that it can lead to tags being added without much scrutiny. Ultimately, pages can become bloated with tags that are no longer needed.

Third-party request map from Performance Analyser

Request maps in Performance Analyser can reveal the extent of third-party content on a page

Understanding the trade-off

So what’s the answer?

For most, removing third parties altogether just isn’t an option. They can bring huge benefits, either directly or indirectly helping organisations maximise revenue. Instead, the key is to realise that third-party services are a trade-off. They deliver value, but there may also be a cost.

Many organisations now have some form of third-party tag governance to help them keep track of the tags they’re using, the benefits they offer and any drawbacks in their implementation. Sometimes, this requires a level of technical insight from IT or operations, as well as input from marketing or ecommerce. On top of keeping a close eye on individual third parties, it’s important to understand their cumulative effect – one synchronously loaded script might have very little impact on how a web page loads and displays (as long as you get a fast response from the third-party). But 20 of them could be disastrous. And the greater the number of tags, the greater the chances that one of them will be slow.

The point to take away is that services designed to increase revenue could be having the opposite effect if they’re slowing the site down. And any value that third-party content offers has to be offset against the impact on page speed.

Learn more about how third parties are affecting your website with a free third-party impact report.

Also in this series:

Ten things every marketer should know about web performance…

1: Why performance matters

2: Big images slow web pages down

3: Traffic affects performance

4: How testing can harm sales

Published date:  29 June 2017

Written by:  Alex Painter

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