Lazy loading can reduce unnecessary image downloads, but applying it indiscriminately can delay the content visitors came to see.
A page’s lead image and a photograph near the bottom of a long article do not have the same loading priority.
A useful strategy starts with the initial viewport, identifies the images needed immediately, and defers images whose absence will not obstruct the first useful view.
Classify images by when they matter
MDN describes lazy loading as a way to defer images outside the initial viewing area instead of downloading the complete image collection immediately.
Its performance guidance also explains that reducing competition from lower-page images can help more important resources load sooner.
For a long article, the opening illustration may deserve immediate discovery and loading. Additional photographs farther down the page can often wait.
Evaluate actual layouts rather than making the decision solely from an image’s position in the content database. A component placed high on desktop may appear differently on a narrow screen.
Use native loading behavior where appropriate
For a lower-page image, a basic implementation can use the browser’s loading attribute:
<img
src="workshop-detail.jpg"
alt="Workstations arranged around the central demonstration table"
width="1200"
height="800"
loading="lazy">The attribute expresses a loading preference without requiring a custom scroll handler.
However, the browser controls the precise loading behavior. Do not design around an assumption that an image will start downloading at one exact pixel boundary.
Test the result under the conditions relevant to the site.
Reserve the image’s space
MDN explains that image dimensions allow the browser to determine an aspect ratio before the image finishes downloading. This helps reserve space and reduce layout movement.
That is especially useful when loading is deferred.
If the page initially gives the image no meaningful space, later loading can push text and controls away from their previous positions. A visitor may lose their reading position or have a target move while approaching it.
Use dimensions that represent the image’s actual proportions, with responsive styling as needed.
Inspect the first useful view
Test the page from a fresh load and watch the opening content.
Does the main image appear promptly? Can the visitor understand the page before scrolling? Are important visuals being deferred because a global setting applied lazy loading to every image?
Then scroll at an ordinary pace and observe the lower sections. Images should appear usefully as the reader reaches them, without disruptive movement.
Use both a narrow and a wide viewport. A loading strategy that behaves well on one layout may need adjustment on another.
Measure the complete experience
Do not judge the change only by the number of requests made at the first instant.
The goal is a useful page that loads efficiently. A smaller initial transfer can coexist with a delayed lead image or an unpleasant scrolling experience.
Compare the same page under consistent conditions and inspect relevant performance measurements alongside the visual result.
Also check templates after content changes. A new hero component or reordered article layout can alter which image is most important.
Lazy loading works best as a priority decision. Load the imagery needed for the opening experience, defer what can wait, and preserve the layout while each image arrives.
Sources: MDN: Image loading and LCP · MDN: Image performance
