Web performance and loading speed testing tools are firmly part of the daily life of Fasterize’s Technical, Sales and Customer teams. Waterfalls and filmstrips are scrutinized for all our customers, before, during and after the deployment of our SaaS solution, and for the application of the advice from our web performance audits.
How do our experts use monitoring solutions, and how are they real pillars for improving our clients’ performance, SEO and conversions (5% to 10% minimum, with peaks of up to 30%!)?
A spotlight on the data we track, and how we use it.
Speed testing before deploying Fasterize SaaS solution
Before deploying Fasterize’s SaaS solution, we evaluate the potential technical and business performance gains . “In addition to Core Web Vitals , which have become essential UX and SEO metrics, we analyze a selection of KPIs to evaluate site performance: Time To First Byte , Start Render , and Speed Index ,” says Nicolas Hodin, Customer Success Engineer Expert. “Also, the filmstrip helps us visualize the pace of page construction as seen by site visitors, with and without the optimizations provided by our SaaS solution. We thus test the loading speed of a page by varying the parameters of our features to find the best adjustments, a task that is intended to be automated.”
Since Google announced its Page Experience algorithm update , queries around Core Web Vitals optimization and Google PageSpeed Insights score have continued to increase. Analytics tools allow you to collect detailed data, which is essential for solving speed issues on sites and for testing the most effective levers.
In practice, Fasterize teams test as a priority a selection of the most important typical pages for a website, such as the homepage, category pages, product pages or even internal search engine results pages (crucial pages, especially for e-commerce sites), before and after optimizing the display speed.
To ensure that the site is fast in all browsing contexts and for all devices, the page test is launched in different contexts: mobile and desktop , with more or less good network quality (3G, 4G, ADSL, etc.), with and without a cookie consent banner, with and without scripts (the Block tab of Web Page Test allows, for example, to simulate browsing with or without scripts activated)… The agents deployed throughout the world are also very useful for international sites, in order to evaluate the impact of optimizations according to geographical areas – because beyond front-end optimization, Fasterize also plays a CDN role with more than 400 points of presence spread across all continents, in order to offer an optimal user experience for visitors around the world.
For our future customers, this data on speed in different browsing contexts makes it possible to anticipate web performance gains , deduce the impact on turnover , and therefore easily estimate the ROI of the SaaS solution . This is what Minelli did, whose e-commerce team estimated that from +0.5% conversions, the solution would be profitable – in other words, the ROI was guaranteed. As for Alltricks, the e-commerce site makes the solution profitable no less than 22 times !
Comparison of page performance with and without front-end optimizations, via Fasterize’s Insights tool that communicates with the Web Page Test API. The percentage in green indicates the performance gains obtained thanks to the optimizations provided by the SaaS solution
Thus, performance monitoring and analysis tools are used to collect essential data for understanding the customer context, and on ways to resolve performance problems.
In short, all the information is at your fingertips to improve the user experience, and to improve the Google PageSpeed Insights score – like for example GO Sport which has seen a significant increase in its PageSpeed Insights: +15 points thanks to the automation of loading speed optimization.
Focus on the waterfall: an x-ray of web page performance
Before undertaking anything to optimize loading speed, the waterfall allows you to detect performance problems and weak points, what blocks rendering… in short, what needs to be optimized. So, for a complete x-ray of a web page, nothing beats a waterfall !
It is also a benchmark for assessing the effectiveness of optimizations once they are automatically applied by our Next-Gen CDN, or by our clients’ internal technical teams following a webperf audit , which we will discuss a little later.
The content of a waterfall is used both to explore the technical aspects of a page and to provide a diagnosis and advice based on elements that are easily understood by the business teams at a client.
On a technical level, the content of a waterfall indicates precisely what can block the critical path. Some examples of what can be observed on a waterfall with the Web Page Test tool, a reference in the webperf community:
- if it has a lot of pink bars, it is a sign of script issues that need to be optimized;
- If some resources are represented by long horizontal bars, it is also a sign that there are optimizations to be made to the weight and size of images , fonts , etc.
Waterfall of a page tested without Fasterize, in HTTP/1.1. the server response time (TTFB) is very long
Waterfall of a page tested with Fasterize: the server response time (TTFB) is divided by 6, and the entire page loading speed is optimized
Waterfall of a page tested without Fasterize: with many requests to external domains, JavaScripts loaded very late, and heavy CSS files that need to be optimized ( minification, concatenation and compression of CSS )
Waterfall of a page tested with Fasterize: all requests are optimized for a faster loading time. Critical resources are loaded 100 ms before the HTML data is received by the browser (thanks to the Early Hints feature )
Measuring Core Web Vitals to Improve User Experience and SEO
Since Google integrated speed into its algorithm, Core Web Vitals have been the focus of attention for the webperf and SEO communities. Web performance testing and analysis tools (Web Page Test, Pingdom, GTmetrix, Dareboost, etc.) but also Lighthouse, PageSpeed Insights, Google Search Console, Chrome Dev Tools, etc.) provide valuable information for analyzing the UX metrics highlighted by Google:
- LCP ,
- CLS
- FID ,
- as well as the Total Blocking Time (TBT), the equivalent of the FID for synthetic environment testing .
Their optimization contributes to better SEO .
In these testing tools, we find the essential data to observe possible layout shifts during loading (CLS), know how to improve the display speed of the most important element on the page (LCP), or identify what prevents the page from meeting Google’s (and obviously users’) requirements in terms of interactivity (FID / TBT).
Finally, our experts rely on the advanced features of testing tools (e.g. Web Page Test scripts) to measure the performance of pages as visitors, but also as a search engine robot, in order to identify and apply the necessary improvements for both UX and SEO. In practice, in terms of SEO, after having automatically optimized their sites:
- TUI.fr saw its number of pages considered fast by Botify doubled ;
- Alltricks increased its SEO traffic by 25% ;
- and SantéVet has quadrupled the number of pages considered fast on Google Search Console .
Whatever our clients’ objectives, before deploying our solution on all of a website’s traffic, we check the impact of all of our platform’s features, and above all, how well they work in relation to each other: intelligent compression and cropping of images in new-generation formats (WebP, AVIF), lazyloading , cache strategy , CDN , prioritization of JS , preloading of key resources , etc. (a list that is obviously far from exhaustive). And after deploying all of these optimizations, how can we ensure that they are effective over time, and that all visitors benefit from them? Thanks to… performance tests.
Monitor the impact of optimizations on loading speed for continuous performance improvement
Once a website’s pages have been optimized by Fasterize, the focus is on increasingly fine-grained web performance issues, to continue to provide ever more advanced solutions. For example, the impact of third-party resources on the critical path, the impact of the font loading strategy on display speed, etc. There are always milliseconds to save, and speed testing tools remain the best way to know what can be improved.
The results of these a posteriori speed tests also feed into the reports submitted regularly for detailed performance monitoring, accompanied by an analysis and personalized advice for configuring the various functionalities of the platform. In addition to the technical KPIs, these reports also highlight the evolution of business data , such as for Mecatechnic which recorded +15% conversions on mobile , or for Carré Blanc which saw its conversions increase by 25% since the implementation of Fasterize.
Thanks to these detailed audits and advice as part of the support by our experts , the impact of webperf optimizations can be understood and monitored by all teams, both business and technical, and the content of the reports shared internally. This is essential to spread the webperf culture ; increase skills , and make it a priority subject.
Finally, webperf monitoring tools are also the cornerstone of our consulting services for teams who wish to optimize their internal performance.
Webperf audit: test the speed of a site for personalized front-end optimization advice
A webperf project necessarily starts with an analysis of the results of speed tests, because we can only improve what we know how to measure. Indeed, to know where to go, we must know where we are starting from.
If you’re interested in web performance, you’ve probably already used PageSpeed Insights, Google’s free tool that provides a performance score and offers front-end optimization advice. While the score is easy to read at first glance —a score between 0 and 100 in red, orange, or green—the optimization advice should be viewed with a grain of salt, as it is generic. The business and technical context of your site is not taken into account, and you’d be wise to consult experts before following this advice to improve your performance.
Some teams have the resources and expertise to implement best practices and front-end optimization techniques, and most importantly, to maintain them in the long term. This involves dedicating time to fixing potential bugs or regressions, and constantly monitoring new techniques and formats to implement them.
To support teams that have the internal resources to optimize their loading speed, Fasterize offers webperf audits and extremely advanced consulting services. In this case, the use of web performance testing tools goes even further than configuring the Fasterize engine, for a manual application.
For the sports daily L’Equipe, the advice from the webperf audit report was the starting point for a major technological leap that involved a complete overhaul of the technical base; for the sports equipment brand Rossignol, the recommended optimizations made it possible to meet UX and business challenges by dividing loading times by 10 at the time; as for the daily newspaper Le Parisien, a detailed performance analysis made it possible to understand and remedy the deterioration of webperf KPIs and Core Web Vitals despite a recent overhaul of their website.
Speed tests are thus present throughout the customer relationship cycle , to aim for ever better performance. From pre-sales to monthly monitoring following the deployment of our SaaS solution for automating webperf optimization techniques, or for advice on optimizing loading speed applied internally, not a day goes by without clicking on “Start test” in order to:
- test the speed of web pages under different conditions (network quality, mobile or desktop devices, geographic area, with or without cookie consent banner, etc.) to ensure that the site is fast for all visitors;
- validate that the thresholds defined by Google are respected for the Core Web Vitals and that the pages are indeed Mobile Friendly;
- analyze the content of waterfalls, and identify the resources that slow down the loading of pages in order to optimize them;
- observe the filmstrips for a concrete visualization of the user experience.
To learn more about the essential metrics to track and how to optimize them:
