Flutter performance tips
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1. Use 'Stateless' instead of methods ( Widget myWidget(){} ) to save GPU
2. Avoid rebuilding all the widgets - ValueNotifier, Provider, Getx is good solutions.
3. Use 'const' wherever possible.
4. Use 'itemExtent' in ListView for long Lists.
5. use AnimatedOpacity() or FadeTransition(), Not AnimatedBuilder() - to avoid build each frame
6. Take a look at the source for full details.