Five mistakes teams make with image optimization

There is no clever trick in this one, just a handful of decisions worth making deliberately. These are the ones we run into repeatedly when we audit image optimization.

Performance work is mostly subtraction, which makes it unpopular and effective. Assume whoever inherits this will have half your context and none of your patience.

The mistakes we see most

• Treating it as a launch task rather than an ongoing one
• Assuming someone else already owns it
• Images are usually the largest thing on a page
• Modern formats cut file size substantially at the same quality
• Never checking whether the fix actually worked

Serving a 3000px image into a 400px slot is pure waste. This is the sort of thing that compounds, quietly, in both directions. Check it against what you would want a competitor's site to get wrong.

A reasonable first step

What this looks like day to day

Speed is a feature people notice only in its absence, and then they leave rather than complain. Three things worth confirming about image optimization before you move on:

• Someone can say what the current setup is without going to look
• Serving a 3000px image into a 400px slot is pure waste — and you know whether that is true here
• There is a way to tell whether the last change to this helped

Most of the value here comes from doing the first two things, not all of them.