Key takeaways
- Speed affects conversions directly. Portent’s 2022 study found B2B sites that load in one second convert at about three times the rate of sites that load in five seconds.
- Small gains count on mobile. In the Deloitte study commissioned by Google, a 0.1-second mobile speed improvement coincided with 8.4% more retail conversions and 10.1% more travel conversions.
- Server-side fixes such as caching, a CDN and faster hosting often deliver the biggest gains, because the browser cannot start until the server responds.
- Faster pages convert more of the visitors who already arrive, even when rankings do not change.
- Measure with field data from real visitors, such as Chrome UX Report data in Search Console, rather than lab scores alone.
Page speed is a conversion metric as well as a technical SEO one. Slower pages lose visitors before they see the offer, and the loss compounds across every campaign that sends traffic to them. This Emulent guide covers what the data shows, which fixes have the most effect on conversions and how to measure speed’s impact on your own site.
What does the data say about speed and conversions?
Several large studies point the same way: faster pages convert better, and the steepest drop comes in the first few seconds.
- Portent’s analysis of B2B and B2C sites found lead-generation pages that load in one second convert at close to 40%, falling to about 29% at three seconds. For ecommerce, conversion rates averaged 3.05% at one second and dropped below 1% by four seconds.
- Deloitte’s Milliseconds Make Millions study, covering 37 brands over four weeks, found that a 0.1-second mobile improvement lifted retail conversions 8.4% and average order value 9.2%, and improved bounce rates on lead-generation pages by 8.3%.
- Portent also reported that most pages already load within five seconds, so the competitive gap now sits between fast and very fast.
Treat these as directional. They describe averages across many sites, and they show association rather than proof that speed alone caused each change. Your own before-and-after data is the better guide.
Speed and rankings work together. Core Web Vitals are part of the page experience signals Google’s ranking systems use, though relevance still comes first. A faster page may rank somewhat better and will convert more of the visitors it receives.
Where do you focus speed improvements for maximum conversion impact?
Start with the metrics visitors feel most, on the pages that bring leads and sales.
| Metric | Where to focus |
|---|---|
| Largest Contentful Paint (LCP) | how fast the main content, usually a hero image or headline, appears. Google’s “good” threshold is 2.5 seconds or less. Compress and correctly size hero images, preload the LCP image and avoid lazy-loading it. |
| Time to First Byte (TTFB) | server response time. Page caching, a CDN and quality hosting cut it most. Emulent hosts WordPress sites on Kinsta, which includes server-level caching and a CDN. |
| Interaction to Next Paint (INP) | how fast the page responds to taps and clicks. The “good” threshold is 200 milliseconds or less. Trim third-party scripts, chat widgets and heavy page builder add-ons. |
| Above-the-fold loading | lazy-load images below the fold, inline critical CSS and defer non-essential JavaScript. |
On WordPress, we remove unused shortcodes, scripts and fonts that slow pages. For ecommerce, we recommend Shopify, which handles hosting, CDN and caching for you, though apps and theme code still need trimming.
How do you measure speed’s impact on your specific conversion rate?
Compare speed and conversion data for the same pages over time.
- Check field data first: Search Console’s Core Web Vitals report and PageSpeed Insights show real-visitor data from the Chrome UX Report for your URLs and origin.
- Measure before and after: record key event rates for affected pages for 30 days before and after a speed change, and adjust for seasonality and campaign changes.
- Segment by speed: send Core Web Vitals values to GA4 with Google’s web-vitals library and compare conversion rates for fast and slow sessions in GA4 explorations or BigQuery.
- Compare page types: service pages, landing pages and blog posts may respond differently, so analyze them separately.
In one Emulent client engagement, reducing a service page’s LCP from 3.8 seconds to 1.6 seconds was followed by a higher form submission rate on that page over the next quarter. Results vary, and other changes can affect conversion rates at the same time.
How can the Emulent team help?
Emulent includes speed work in our technical SEO and conversion services, connecting your SEO infrastructure to lead and revenue results. We find the bottlenecks on the pages that bring business, fix them and measure the effect on conversions. A caveat: lab scores such as Lighthouse can differ widely from what real visitors experience, so judge progress by field data and conversion rates. Contact the Emulent team to speed up the pages that drive leads.