In our daily work as a web performance agency, prospects and clients contact us every day to audit and optimize their websites. The initial conversations are usually of the type "my site is slow, I want it to be faster". This is true regardless of their industry: e-commerce, publishers, or specialized brands all face the same issue of slowness, with the desire to offer visitors a fast-loading site.
When we dig deeper to better understand their issues, motivations, and goals, we find that they are quite different profiles.
What exactly is a fast website?
A website is considered fast when it meets the three Core Web Vitals thresholds in the field: an LCP below 2.5 seconds, a CLS below 0.1, and an INP below 200 milliseconds. These thresholds are assessed at the 75th percentile of visits, meaning for three out of four visitors, including those on modest devices and slow connections.
The distinction is crucial because it shifts the focus from perception to measurable fact. A site that appears instantaneous on a fiber optic connection at the office may fail all three thresholds on a 4G mobile connection. Speed is not judged on your machine, but on the actual distribution of visits, as reported by Chrome's field data.
These indicators and their measurement methods are detailed in our guide to web performance and its measurement. Remember here that a speed objective is not formulated as 'faster,' but in quantified, third-party verifiable thresholds.
Why is a fast website important?
A fast website serves three objectives simultaneously: it converts more, because a visitor who waits abandons; it ranks better, as speed is a Google ranking factor; and it costs less to serve. The three benefits accumulate without ever conflicting, which is rare in technical trade-offs.
In the eyes of a majority of web publishers, generally small and medium-sized, a site's loading speed is primarily a matter of SEO. Their primary and often sole motivation is simple: gain visibility in Google's search results pages (the famous SERPs). While web performance and SEO are intimately linked through the Page Experience aspect and Core Web Vitals, they thus overlook a whole part of the potential of performance optimization.
For another part of our clients, typically large accounts with an e-commerce activity, it's the complete opposite! They only see the User Experience aspect, with the deeply ingrained idea that reduced loading times will improve their commercial performance. Conversion rates, average session duration, average order value, and revenue are, in their eyes, all related to having a fast site. They are not wrong, obviously, but they also wear blinders specific to their profession.
The truth is that a fast website is an issue for SEO, UX, but much more. A fast site in terms of loading (FCP, LCP, Speed Index metrics...) and user interactions (TBT, INP metrics...) is essential for establishing a lasting presence in a competitive sector. It's a quality assurance, an invisible pre-sales service, or the best vector for your brand image. You take care of your visitors, and rest assured: they will notice!
Is your site as fast as your visitors expect?
These effects are documented by published measurements, not just intuition. Google lists in its file on the business impact of Core Web Vitals the case of Vodafone Italy, whose 31% improvement in LCP resulted in 8% more sales, or Cdiscount, which saw 6% more revenue during a Black Friday.
Bounce rate reacts just as sharply. Still according to case studies compiled by Google, Agrofy observed 76% fewer drop-offs during loading after improving its LCP by 70%, and NDTV halved its bounce rate by halving its LCP. These orders of magnitude are not directly transferable to your site, but they indicate the scale of what's at stake.
How can we have a fast website?
Two paths lead to a fast website: integrating performance from the design phase, which is the cheapest, or optimizing an existing site, which requires measurement before action. In both cases, performance is decided in the specifications, at the time of choosing the stack, hosting, and templates.
Having a high-performing website isn't something everyone can do. The best way to avoid mistakes is to integrate speed considerations from the design of your site. By being proactive with specifications that mention web performance, you'll at least have the assurance that the issue hasn't been completely ignored. Because, sadly, a large majority of web design agencies still know nothing about what web performance is, let alone the tricks of the trade.
If the problem has not been anticipated, the solution is to turn to specialists, and certainly not to a generalist web agency. We are promoting our own services here, but we regularly observe the following unfortunate fact: many agencies will tell you that they can handle speed issues and that they have the internal resources to intervene. Some of our prospects make this choice, and return to us a few months later with bitterness, less cash flow, and the desire to finally resolve their site's slowness.
Transforming a slow site into a fast one requires advanced skills, front-end developer experience, and an excellent understanding of how web browsers work. These are all qualities our teams possess, and that we make available to you as part of our performance optimization services.
On an existing site, the order of work matters as much as the work itself. The first item to examine is the server response time, as it delays everything that follows: no image optimization can make up for a server that responds in two seconds. Caching and hosting therefore come before the front-end, never the other way around.
Next come the rendering levers: the page's main image, whose weight and priority determine the LCP; third-party scripts, primarily responsible for interaction blocking; fonts; and the reserved dimensions for elements that load late. These four items cover the majority of gains observed on a standard site.
This leaves the question of long-term maintenance. An optimized site left unattended becomes slow again in a few months, with the pace of publications, added extensions, and stacked marketing scripts. Performance is a state to be maintained, not a project that is finished, which explains the role of monitoring in our support.
What is the cost of a fast website?
The cost of a fast site breaks down into two parts: a one-time investment, that of the audit and then optimizations or redesign, and a recurring cost, that of hosting and maintenance which prevent performance from degrading. The second is often forgotten in budgets, even though it is what makes the first one sustainable.
As you've understood, whether for a new build/redesign or for optimizing an existing site, web performance is a matter for specialists. Specialists mean high added value, and high added value necessarily means cost/budget. Assume that if a freelancer or agency gives you a commercial proposal for a few hundred euros, there's a strong chance it's too good to be true. At Agence Web Performance, like other recognized specialists, we use rates based on the daily rate of a senior consultant (around €900-1000/day).
To create or transform an existing site into a fast one (mobile PageSpeed Insights score of 100%), you will need to allocate a real budget to it. It is a project whose cost/benefit ratio is calculated, which is planned within an existing roadmap, and whose benefits are multiple. Combined with careful SEO work, it is the assurance of meeting the expectations of your visitors, search engines, but also your partners, suppliers, etc.
The recurring cost, on the other hand, is straightforward: our performant WordPress hosting offer amounts to €450 excl. tax per month for an all-inclusive package, including management, maintenance, backups, and monitoring. This is the ballpark figure for a site kept up to standard all year round, to be compared with the cost of a redesign necessitated by years without maintenance.
The calculation then works the other way. One conversion point gained on a store, tens of thousands of additional page views on an editorial site, or simply visitors who no longer leave before the page loads: this is what speed brings, and it is this amount, unique to each site, that determines if the investment is justified.
