Mobile performance for small teams

The version of this that works is simpler than the version most people imagine. Most advice about mobile performance assumes a team that does not exist at your size. Here is the version that does not.

Real-world numbers from actual visitors matter more than a score produced on a fast laptop. It rarely shows up as a line item, which is exactly why it slips.

What to keep

Phones have less processing power and worse networks. There is a version of this that is over-engineered, and it is worth avoiding. Write the reasoning down alongside the decision, because the reasoning is what changes first.

What to drop

Process that exists to coordinate ten people is overhead when there are two of you. That sounds obvious written down. It is still the thing most often skipped.

Where to start

JavaScript costs far more on mobile than on desktop. Getting it slightly wrong is survivable. Ignoring it entirely is not. Anything you cannot measure here, you are deciding by taste, which is fine as long as everyone knows it.

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 mobile performance before you move on:

• Someone can say what the current setup is without going to look
• Test on mid-range devices, not just the newest — and you know whether that is true here
• There is a way to tell whether the last change to this helped

None of this needs a rewrite. Most of it is a morning's work once someone decides to do it.