In brief: Lazy loading delays loading an image, video or other part of a page until the content is needed. Used correctly, it saves transfer and time; used poorly, it can delay the main content.
How I use Lazy loading in practice
I assess lazy loading in the context of the entire page. The heading, text, controls, speed and feedback must together explain what can be done and what will follow. I first fix obstacles that prevent the task; decoration and effects come only after the basics work.
What to watch out for
A component is not finished just because it works with a mouse. With Lazy loading I check keyboard use, contrast, zoom, screen reader, slow network and the no-script state. Accessibility and performance are not extras; they are part of the same experience.
Questions for a decision
- What task does the person want to complete on the page?
- Where might they hesitate, make a mistake or lose context?
- Does the solution work on mobile, with a keyboard and on a slow network?
- What signal will show that the change genuinely helped?