Choose journeys to measure
Select a home page, a service page, an image-heavy listing, an article and the contact form. Test at least one mobile and one desktop width with representative devices and connections. Record the date, recent changes and elements visible in the first viewport.
Separate laboratory measurements, which help reproduce a problem, from available field data, which describes real visitor experience. If traffic is too low for a stable measure, do not present one score as a trend. web.dev explains measurement tools and their uses.
- Selected pages and devices.
- Reproducible baseline.
- Task the visitor needs to complete.
Find the reason for slow loading
Identify the main element visible during loading and the resource that supplies it. An oversized hero photograph, late request or script dependency can delay LCP. Use an image suited to its displayed size, with HTML dimensions, responsive variants and sensible priority; do not defer the main image without reason.
Then examine fonts, CSS, JavaScript and server responses. Remove genuinely unused resources and avoid downloading every off-screen card immediately. The image guide covers visual preparation and alternatives.
Prevent shifts and keep interactions responsive
Reserve space for images, embeds and messages that appear after loading. Check CLS throughout reading, not only in the first screenshot. Late fonts and banners can move a button just as a visitor tries to use it.
For INP, try important actions: open a menu, filter a list, choose an option and correct a form. If the response is slow, inspect long JavaScript tasks and the rendering triggered by each action. A simpler interface may help more than another library.
Set a budget and check after release
Set proportionate limits for main images, cards and new scripts. Compare bytes actually downloaded on mobile rather than the total size of the image library. Record what was removed, compressed or deferred and confirm that visual quality and accessibility remain sound.
Repeat journeys after each change and after deployment. Follow LCP, INP and CLS when real-user data is available, without promising that a score guarantees search ranking. Google guidance on page experience puts these metrics within the broader usefulness of the site.
- Bytes and delays before and after.
- No visual or functional regression.
- Checks on priority pages and devices.