Getting started with lazy loading
This is cheap to get right at the start and expensive to retrofit. A short on-ramp to lazy loading for teams who have not touched it before.
Real-world numbers from actual visitors matter more than a score produced on a fast laptop. It is the sort of thing that looks like polish right up until it costs you an enquiry.
Why it matters
Only load what is about to be seen. There is a version of this that is over-engineered, and it is worth avoiding. Assume whoever inherits this will have half your context and none of your patience.
Your first week
- Find out what is already in place
- Never lazy-load the main hero image
- Change one thing and measure it
Always reserve the space so nothing jumps. Small and consistent beats large and occasional here. Check it against what you would want a competitor's site to get wrong.
How to tell if yours is fine
Speed is a feature people notice only in its absence, and then they leave rather than complain. Three things worth confirming about lazy loading before you move on:
- Someone can say what the current setup is without going to look
- Only load what is about to be seen — and you know whether that is true here
- There is a way to tell whether the last change to this helped
If you are not sure where your systems currently stand on this, it takes us about an hour to find out.