Conversion rate is the percentage of visitors who complete the action a page is built for: a purchase, a sign-up, a form submission, a call. It is the metric that connects performance work to money, because every speed improvement is a bet that a faster page keeps more of the visitors you already paid to attract.
What we measure, and what we don’t
We should be straight about this on the page where the temptation is greatest. We have no conversion data of our own. Our audit base holds load metrics for the sites we have measured, and nothing about what their visitors did next. We do not run their analytics, we cannot see their checkouts, and we have not run a controlled experiment where the only variable was page speed.
So every conversion figure you see quoted in this industry, ours included, comes from somebody else’s study: retail case studies, Google’s own research, vendor write-ups of single deployments. Those are worth reading and they point consistently in one direction. They are not a measurement of your site, and anyone presenting them as a forecast for your site is selling.
What we can measure for you is the input rather than the outcome: LCP, CLS, the PageSpeed score, before and after, on your own URL.
Why speed moves it anyway
The mechanism is not controversial, even where the magnitude is:
- Bounce rises with load time. A visitor who leaves before the page renders cannot convert, and the probability of leaving climbs steeply through the first few seconds.
- The first paint sets the impression. LCP is what a visitor actually feels as fast or slow. A late hero image reads as a broken site even when everything behind it works.
- It compounds with paid traffic. If you buy clicks, a slow landing page wastes a fixed share of that spend on people who leave, so a speed fix lowers cost per acquisition without touching the bid.
Speed is a lever, not the machine
Conversion rate is driven by your offer, price, copy, trust and audience at least as much as by load time. A fast page with a weak offer still will not convert. What speed does is remove a tax: it stops you losing visitors who would have converted but left while waiting. Treat a speed win as recovering lost demand, not as manufacturing new demand.
How WebSpeed fits in
WebSpeed’s job is the removable tax. By pulling LCP and FCP earlier and lifting the PageSpeed score, it keeps more of your existing visitors in the funnel long enough to see your offer. Because it shows a real before and after on your own page, you can reason about the gain in terms of the visitors it saves, and then check against your own analytics, which is the only place the answer actually lives.