Understanding PureComponent in React

'PureComponent' in React is a special type of component that helps optimize performance of your React applications. The main function of a PureComponent is to prevent re-rendering if the props and state have not changed.

Here is a practical example to help you understand:

class MyComponent extends React.PureComponent {
    render() {
        return <div>{this.props.name}</div>;
    }
}

In the code above, if the 'name' prop does not change, then the 'MyComponent' instance will not re-render, ensuring the system only uses the resources necessary for rendering when changes occur.

This is immensely beneficial in large scale applications where even the slightest performance enhancement can make a significant difference in the overall efficiency of the application.

However, one thing to keep in mind is that the PureComponent uses a shallow comparison on the state and props. This means that if you pass complex data structures like objects or arrays as props and mutate them without changing their reference, React wouldn't notice the changes and wouldn't re-render the component.

It's a best practice to use immutable data structures and pure functions without side effects in conjunction with PureComponent. Side effects could lead to bugs which are hard to spot because the component will render with state and props that haven't changed according to the shallow compare.

So, while 'PureComponent' can enhance your component's performance by preventing unnecessary re-rendering, careful consideration is needed of when and how you use it to avoid potential issues related to shallow comparison of complex props or state.