12 July 2026 · Kenya Web Studio

Core Web Vitals on Kenyan mobile connections

Use LCP, INP and CLS to find slow loading, delayed taps and moving layouts. Then test the actual pages and phones your customers use.

The three measurements cover different problems

Largest Contentful Paint measures how long the main visible content takes to appear. Interaction to Next Paint measures how quickly the page gives visual feedback after a click, tap or keyboard action. Cumulative Layout Shift measures unexpected movement while the page loads.

Google’s published good thresholds are LCP within 2.5 seconds, INP at or below 200 milliseconds and CLS at or below 0.1. Field assessment uses the 75th percentile, split by mobile and desktop. Those numbers are diagnostic targets, not a substitute for opening the site on a phone and trying to use it.

Field data and lab tests answer different questions

PageSpeed Insights can show Chrome User Experience Report field data when a page or origin has enough traffic. Field data describes visits by real Chrome users over a rolling period. It includes devices and network conditions you do not control.

Lighthouse runs a simulated test. It helps a developer reproduce faults and compare changes, but one perfect score does not prove every customer gets a fast page. Use field data to see the problem and lab tools to investigate it. Search Console’s Core Web Vitals report helps group affected URLs.

Large images usually hurt before fancy code does

A home page can send several megabytes before the visitor reads one sentence. Full-resolution project photographs, uncompressed PNG files and background video are common causes. Resize each image for its display slot, use a suitable modern format and let responsive markup send smaller files to smaller screens.

Do not lazy-load the main image that defines the first screen. The browser needs to discover it early. Images lower on the page can load later. Always reserve their width and height so text does not jump when they arrive.

Inspect the LCP element instead of guessing
Remove hidden mobile images that still download
Set image dimensions or an aspect ratio
Avoid autoplay video in the first screen
Check third-party widgets before blaming the hosting plan

JavaScript can make a loaded page feel stuck

A page may look ready while the browser is busy parsing code or running a long task. The user taps the menu and nothing moves. That delay appears in INP. Large client bundles, chat widgets, analytics tags and poorly written event handlers all deserve inspection.

Send plain HTML for content where possible. Load interaction code only where it is used, break up long work and avoid rendering hundreds of hidden items. A brochure site should not ship the same browser workload as a stock-trading screen.

Test under limits that expose the fault

Office fibre can hide a bad build. Test on a mid-range Android phone, use mobile data and try a throttled lab run. Reload without a warm cache. Open the menu, submit the form and return to a page with the Back button.

Test every page people enter through. The home page is only one of them. A compressed home page does not help if the product page carries six unscaled photographs or the contact page waits for a heavy map script. Check important templates separately.

Fix in the order customers feel it

Start with pages that bring enquiries or sales. Find the largest delays and layout jumps, make one change, deploy it and measure again. Keep a short record of what changed so a later plugin or tag addition does not quietly undo the work.

Performance work is maintenance. Product catalogues grow, teams upload new images and marketing scripts creep into the header. Put file-size limits and review steps into the publishing process rather than scheduling a rescue once a year.

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