A slow mobile website: what to check first

“Make the website faster” is a broad request. Start with the task that feels slow: opening a service page, selecting a date or completing checkout. A fast homepage does not tell you whether the pages that generate business are usable.

Separate different kinds of delay

A page can show its main content late, respond slowly to a tap or move buttons while loading. These are different problems. Google’s Web Vitals guidance describes LCP, INP and CLS as measures of loading, responsiveness and visual stability. Use them to locate issues, rather than treating one score as the entire customer experience.

Compare repeatable test results with available measurements from real visitors. A single run on a powerful office computer may miss the problem a customer experiences on a phone.

Check what the page asks the phone to load

Large photographs, unnecessary video and multiple external widgets are practical starting points for an audit. Ask whether images are delivered at an appropriate size and whether off-screen content needs to load immediately. Keep the important first-screen content available promptly.

Review chat tools, advertising tags, maps and embedded booking components. Remove tools that no longer serve a purpose and test whether essential integrations can load without delaying the main task. Do not remove a business-critical component just to improve a measurement.

Check the response behind the screen

If a calendar waits several seconds after every selection, image compression may not solve it. The delay could be in the application, data request or external service. Measure that specific interaction and give the person responsible a reproducible example.

After each change, repeat the same task on the same test conditions and check that bookings, payments and forms still work. Record the before-and-after results. Prioritise changes that improve a meaningful customer task, and review again when new content or integrations are introduced.