Case Study: The UK's Leading Health Retailer quantifies page-speed impact to protect revenue with SiteSpect

UK’s Leading Health Retailer - Customer Case Study

The UK’s leading health retailer—operating over 1,300 stores and a fast-growing online division—was working with SiteSpect to optimize UX and wanted to quantify how page speed affects conversions. Although their deployment method avoided the typical speed penalties of tag-based tools, the UX team needed concrete data to prioritize roadmap decisions and weigh the cost/benefit of changes that could add latency.

Using SiteSpect, they ran a 50/50 A/B test that simulated a one‑second page‑load delay by hiding page content with CSS for one second. The result: purchase conversion fell by 10.83% (p < 0.01), an estimated ~£10,000 less revenue per day when extrapolated to all traffic; mobile dropped 4.38%, new users dropped 16.56% (99% significance) and returning users 6.97% (82% significance). The test was ended once statistical significance was reached, and its insights are now being used to prioritize projects by their page‑speed impact.