Getting started with mobile performance
The gap between knowing this and actually doing it is where most teams lose ground. A short on-ramp to mobile performance for teams who have not touched it before.
Performance work is mostly subtraction, which makes it unpopular and effective. Anything you cannot measure here, you are deciding by taste, which is fine as long as everyone knows it.
Why it matters
Phones have less processing power and worse networks. There is a version of this that is over-engineered, and it is worth avoiding. The version that survives contact with a real deadline is the simple one.
Your first week
- Find out what is already in place
- Test on mid-range devices, not just the newest
- Change one thing and measure it
JavaScript costs far more on mobile than on desktop. Small and consistent beats large and occasional here. It rarely shows up as a line item, which is exactly why it slips.
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
- JavaScript costs far more on mobile than on desktop — 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.