0
Performance · Advanced Performance
New technique
The performance loop
A master smith doesn't polish once and walk away. Measure, budget, fix, watch, and round again.
Performance isn't a one-off job. Every new feature and dependency can slow things down again, so pros work in a loop.
- Measure with both lab tools (Lighthouse, WebPageTest, DevTools) and field data (RUM, CrUX).
- Budget: agree on limits, like JS size and LCP, and check them automatically.
- Optimize the biggest bottleneck the numbers show, not a hunch.
- Monitor real users continuously; devices, networks and your code keep changing.
- In DevTools, turn on CPU and network throttling: your laptop is far faster than a typical phone, and a problem that takes 800 ms on a phone may take 80 ms on your machine.