What to ask your agency about mobile performance

The gap between knowing this and actually doing it is where most teams lose ground. If you are briefing an agency or a freelancer on mobile performance, these questions are worth asking early.

Real-world numbers from actual visitors matter more than a score produced on a fast laptop. If it only works because one person remembers to do something, it does not work yet.

Questions worth asking

• Who will actually do this work, and have they done it before?
• How will we know afterwards whether it worked?
• What happens if it needs changing in a year?
• What are you assuming that we have not confirmed?

What a good answer sounds like

Phones have less processing power and worse networks. The cost of getting this wrong is rarely visible on the day it happens. It is worth deciding this deliberately rather than inheriting whatever the last person set up.

JavaScript costs far more on mobile than on desktop. This is the sort of thing that compounds, quietly, in both directions. Most teams find the first pass takes an afternoon and the maintenance takes minutes a month.

The short version

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

• Someone can say what the current setup is without going to look
• Phones have less processing power and worse networks — 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.