How to put a euro figure on your landing page's load time, find the usual causes of a slow page and fix the biggest ones, often without a development project.
Most businesses treat page speed as a technical matter: a job for the developer, measured in scores nobody in the marketing meeting looks at. Yet every euro you spend on ads buys a click that lands on a page. If that page is slow, some of the people you paid for leave before they see your offer, and the rest are a little less willing to buy.
There is no honest universal figure for what one second costs, because it depends on your traffic, your audience and your margins, but you can work it out for your own site. A slow page loses conversions, and on paid traffic every lost conversion raises your cost per customer. If slow loading loses one in ten visitors who would have bought, each customer you still win costs about 11% more, on every campaign that sends people to that page.
This article shows how to put a euro figure on your load time, how to measure what visitors actually experience, which problems cause most slow landing pages and which fixes need no developer. The aim is to treat speed like any channel you invest in, with a cost, a return and an owner.
A slow landing page costs you in three ways. Some visitors leave before anything appears, but you have already paid for their click. Those who wait are less patient with the rest of the page, so fewer of them finish a form or a checkout. And because ad platforms learn from the conversions you report back to them, fewer conversions give their automated bidding less to learn from.
The platforms also judge the page itself. Google Ads assesses landing page experience as part of ad quality, which affects where your ad appears and what you pay per click. On Meta, the leak is visible in your own reports: compare link clicks with landing page views, which count only the people whose page loaded far enough for the Meta pixel, Meta's tracking code on your site, to record the visit.
In Europe, part of that gap is people who decline cookies, so watch the trend rather than the absolute number; a gap that widens after a site change is a strong sign the page got slower. Check mobile first. Paid social traffic is mostly mobile, opens inside the app's built-in browser and is often a first visit, with nothing stored from earlier visits to speed things up.
Say you spend €10,000 a month on Google Ads at an average of €1 per click, which buys about 10,000 visits. At a 2% conversion rate, meaning 2 in every 100 visitors buy, you win 200 customers at €50 each in media cost. These figures are an illustration, not a benchmark.
Now assume a faster page lifts the conversion rate to 2.3%. The same €10,000 buys 230 customers at about €43 each: 30 more customers a month without changing bids, budgets or ads. If each customer brings €60 of gross margin, that is €1,800 a month, or more than €20,000 a year, from one improvement.
Turn this into a decision rule. Estimate a realistic lift for your page, multiply the extra conversions by your margin per sale, and compare the monthly result with the one-off cost of the fix. If a developer quotes €1,500, the fix pays for itself after 25 extra sales at €60 margin, which in the example above would take less than a month.
To judge what lift is realistic, compare mobile and desktop conversion rates for the same page in GA4, Google Analytics 4. A large gap on a page that is slow on mobile suggests speed is part of the problem, although people also research on phones and buy on laptops, so treat it as a clue rather than proof.
Start with PageSpeed Insights, Google's free testing tool, and look at the mobile results for the exact page your ads point to. If the page has enough traffic, the report shows how it performed for real Chrome users over the previous 28 days; below that is a lab test that simulates a mid-range phone on a slow mobile connection. The real-user figures tell you how big the problem is, and the lab test helps you find the causes.
Three measures, which Google calls Core Web Vitals, matter most. Largest Contentful Paint (LCP) is when the main content, usually the large image or headline at the top, has appeared; Interaction to Next Paint (INP) is how quickly the page responds when someone taps, clicks or types; Cumulative Layout Shift (CLS) is how much the content jumps around unexpectedly, which is what makes people tap the wrong button. Google rates an LCP of 2.5 seconds or less, an INP of 200 milliseconds or less and a CLS of 0.1 or less as good.
Don't chase the overall score out of 100. It is a lab estimate that moves between runs, and a page can score 70 and sell well or score 95 and still lose people to a confusing form. Test the page as visitors meet it, with the cookie banner and tracking tags in place, because that is the version you pay to send traffic to.
Most slow landing pages suffer from the same handful of problems. Work through them in this order, since the first two are common and usually cheap to fix.
Two more culprits are easy to miss. A cookie consent banner is itself a script, and a slow one can hold up everything behind it. Some A/B testing tools, which show different versions of a page to different visitors, hide the page until they have loaded, so a visitor on a weak connection briefly sees nothing at all.
Much of the improvement on a typical landing page needs no custom code. Most website builders, shop platforms and WordPress set-ups can handle the first three steps below through settings or a plugin, and the rest are decisions rather than development.
Measure again after each change so you know what made the difference. Use the lab test for quick feedback, because the real-user figures cover the previous 28 days and take up to four weeks to reflect a fix. On many pages these steps alone can bring the main content in under Google's 2.5-second mark; where they don't, you have a precise list to give a developer, which keeps the project short.
Speed slips because nobody owns it. A new pixel for a campaign, a larger video at the top, a review widget: each addition is reasonable on its own, and together they undo last quarter's work. Give one person responsibility for landing page speed, with a simple budget such as main content visible within 2.5 seconds on mobile for real users, and no new script without removing another or justifying it.
Then report speed in the same place as spend. When load time sits next to conversion rate and cost per acquisition (CPA), what you pay in media for each sale or lead, it stops being a developer's statistic and becomes part of the media budget.
There is little point paying to test new ads on a page that loses people before it has finished loading.