gpui-performance

# GPUI Performance Optimization

## Metadata

This skill provides comprehensive guidance on optimizing GPUI applications for rendering performance, memory efficiency, and overall runtime speed.

## Instructions

### Rendering Optimization

#### Understanding the Render Cycle

```
State Change → cx.notify() → Render → Layout → Paint → Display
```

**Key Points**:
- Only call `cx.notify()` when state actually changes
- Minimize work in `render()` method
- Cache expensive computations
- Reduce element count and nesting

#### Avoiding Unnecessary Renders

```rust
// BAD: Renders on every frame
impl MyComponent {
    fn start_animation(&mut self, cx: &mut ViewContext<Self>) {
        cx.spawn(|this, mut cx| async move {
            loop {
                cx.update(|_, cx| cx.notify()).ok();  // Forces rerender!
                Timer::after(Duration::from_millis(16)).await;
            }
        }).detach();
    }
}

// GOOD: Only render when state changes
impl MyComponent {
    fn update_value(&mut self, new_value: i32, cx: &mut ViewContext<Self>) {
        if self.value != new_value {
            self.value = new_value;
            cx.notify();  // Only notify on actual change
        }
    }
}
```

#### Optimize Subscription Updates

```rust
// BAD: Always rerenders on model change
let _subscription = cx.observe(&model, |_, _, cx| {
    cx.notify();  // Rerenders even if nothing relevant changed
});

// GOOD: Selective updates
let _subscription = cx.observe(&model, |this, model, cx| {
    let data = model.read(cx);

    // Only rerender if relevant field changed
    if data.relevant_field != this.cached_field {
        this.cached_field = data.relevant_field.clone();
        cx.notify();
    }
});
```

#### Memoization Pattern

```rust
use std::cell::RefCell;
use std::collections::hash_map::DefaultHasher;
use std::hash::{Hash, Hasher};

struct MemoizedComponent {
    model: Model<Data>,
    cached_result: RefCell<Option<(u64, String)>>,  // (hash, result)
}

impl Memoi