Explain Flutter rendering pipeline and optimization.

Flutter rendering pipeline:\n\n**Rendering Pipeline Stages:**\n1. **Build** - Widget tree construction\n2. **Layout** - Size and position calculation\n3. **Paint** - Drawing operations\n4. **Composite** - Layer composition\n\n**Optimization Strategies:**\n• **Const constructors** - Avoid unnecessary rebuilds\n• **RepaintBoundary** - Isolate expensive widgets\n• **ListView.builder** - Lazy loading for lists\n• **Image caching** - Reduce memory usage\n• **Tree shaking** - Remove unused code\n\n**Performance Tools:**\n• Flutter Inspector - Widget tree analysis\n• Performance Overlay - FPS monitoring\n• Dart DevTools - Memory profiling\n• Timeline view - Frame analysis\n\n**Best Practices:**\n• Minimize widget rebuilds\n• Use appropriate list widgets\n• Optimize image loading\n• Profile before optimizing\n• Use release builds for testing