Working efficiently.
WHAT PREVIEWS PROVIDE
Rendering views during development, without running the application.
WHAT THAT ENABLES
Seeing every state, size, theme and language quickly.
WHAT TO PREVIEW
Every state a view supports: default, loading, empty, error.
WHY
It is the fastest way to ensure they all exist and look correct.
WHAT MAKES PREVIEWS WORK
Views that receive their data rather than fetching it.
WHY THAT MATTERS
A view that fetches cannot be previewed meaningfully.
WHAT CAUSES PERFORMANCE PROBLEMS
Heavy work in the view body Views that invalidate more than necessary Non-lazy containers with many children Expensive computation on every update
WHAT TO DO
Move computation out of the body Use lazy containers for long content Provide stable identity
WHAT TO MEASURE WITH
The profiling instruments, and the framework's own diagnostics.
WHY MEASURE
Guessing about what updates is unreliable.
WHAT TO TEST ON
An older physical device.
