Memory Leak After Cursor Refactored Cleanup Code

1. useEffect cleanup function removed or broken
2. Event listener added but never removed (addEventListener without removeEventListener)
3. Subscription created but not unsubscribed (Observable)
4. Timers (setInterval/setTimeout) not cleared
5. References held to DOM nodes preventing garbage collection

useEffect cleanup returns function: useEffect(() => { return () => cleanup; }, []). Remove listeners: window.removeEventListener('scroll', handler). Clear timers: clearInterval(id). Unsubscribe: subscription.unsubscribe(). Use Chrome DevTools Memory tab to detect leaks.