Three myths about lazy loading

This is one of those topics that looks small until it costs you something. A few things about lazy loading that get repeated more often than they get checked.

Speed is a feature people notice only in its absence, and then they leave rather than complain. The version that survives contact with a real deadline is the simple one.

“It only matters for big sites”

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.

“We can deal with it after launch”

Sometimes true, usually expensive. Small and consistent beats large and occasional here.

“Our platform handles it”

Always reserve the space so nothing jumps. The teams that handle this well are rarely the ones with the biggest budgets. The version that survives contact with a real deadline is the simple one.

How to tell if yours is fine

Real-world numbers from actual visitors matter more than a score produced on a fast laptop. 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 any of that sounds like a description of your current setup, it is fixable.