It has been well documented that site speed is a major factor in business success for e-commerce websites. If you can demonstrate that improving page load times by 500ms increases revenue by 5% there is a clear return on investment to make the speed improvements.
Digital publishing has not had so much documented evidence for the benefits for site speed. There are multiple factors behind this, based on the business model of the site. Subscription-based publishers have a captive audience - if you've already paid to access content, surely an article loading a second slower won't stop you reading the content? For ad-driven publishers there is a conflict between AdOps teams piling on tens or hundreds of third-party tags (each promising a slice of ad revenue) and the development team trying to ship editorial content.
Optimizely added artificial latency to the Telegraph and saw page views plummet: by 11% for a 4 second delay and 44% for a 20 second delay.
There are two angles to look at site speed for subscription-based publishers: acquisition and retention. When acquiring new subscribers, these sites can be viewed very much like an ecommerce player - you're trying to convert users from paying nothing to purchasing a subscription.
The e-commerce model does not work when it comes to retention, however. Once a user has purchased a subscription they will have a choice of whether to renew or not. That decision will be based at least partly on their experience of the product over the previous period, there will be a calculation of the value of the content they consume versus the ongoing cost of subscription.
As the FT found out, slower pages result in fewer articles viewed. The drop in articles gets worse over time, presumably as subscribers get increasingly frustrated.
Financial Times added a one second delay to every page view and saw a 4.9% drop in the number of articles users read over a 7 day window. A two-second delay resulted in a 4.4% drop, and a three second delay saw a 7.2% drop. After twenty-eight days the two and three second variants both resulted in further drops in engagement.
Whilst the FT study clearly showed a direct correlation between speed and articles consumed, they did not continue to measure the effect on subscription renewal. It is fair to assume, though, that subscribers who have a poor experience (and thus consume less content) are less likely to renew their subscription. You may be missing out on critical business data if you're not tracking subscriber views, performance and attrition.
GQ cut load time by 80% and saw an 80% increase in traffic. Median time spent on the site also increased by 32%.
The interactive chart below shows the relationship between load time and the likelihood that a user will bounce or continue to a different page (retention) for a range of publishing websites.
The standard e-commerce model again does not work for publishers who make the majority of their revenue from advertising. Success is measured by ads viewed and interactions. There are a number of ways that performance impacts these key metrics:
- Slow pages lead to higher bounce rates
- Slow pages lead to lower interaction rates
- Slow pages lead to poorer organic SEO rankings
- Slow pages lead to higher ad costs
At the most basic level, we know that faster pages lead to an increase in page views. This increase comes from a number of factors: reducing bounce rate (is this page ever going to load?), increasing session length (I've only got a minute to catch up on the news) and favourable rankings from search engines which include speed as a ranking factor. Assuming that there is a near-linear relationship between page views and ad revenue, there is an obvious benefit to improving site speed.
Tokopedia reduced render time from 14s to 2s for 3G connections and saw a 19% increase in visitors, 35% increase in total sessions, 7% increase in new users, 17% increase in active users and 16% increase in sessions per user.
The interactive chart below shows the relationship between first-page load time and session length (pages viewed per session) for a range of publishing websites. Session length can drop by over 60% when comparing the fastest page loads with the slowest!
Sponsored content, takeovers and advertorials
The publishing industry is looking to monetise their visits in novel ways as ad & content blockers become more prevalent. Full page takeovers fill otherwise unused whitespace on the page with sponsored promotional material. The commercial arrangement is similar to sponsored content and is typically based on the duration of the takeover or a goal number of pageviews. Increasing pageviews means either higher value for a duration-based takeover, or a shorter duration for a pageview-based takeover. Either way, this could mean more revenue for the publisher. On a secondary note, takeover content should load after the main content of the page. Making the page faster will mean that the promotional content will be loaded sooner and thus seen by more visitors.
Site speed should be measured using metrics which are closest to user experience. Time to interactive & first meaningful paint are generally the best metrics to use for publishing sites where third-party content may significantly skew the load event. Some key methods to improve time to interactive and paint timing metrics are to prioritise critical content:
- Keep HTML documents < 14kB to maximise the first round-trip
- Use the
loading='lazy'attribute (cautiously) to defer non-critical iframes and images
preloadfor critical fonts
font-display: swapto improve render times
- Keep track of third-party tags
- Remove unnecessary and unused third-party tags
If you would like advice on measuring, improving and advocating for site speed, please get in touch!