Boosting web performance with HTML5 features can greatly improve the speed and efficiency of your website. Here are some HTML5 features and techniques you can use to enhance your web performance:

1. Semantic HTML: Use HTML5's semantic elements like <header>, <nav>, <main>, <article>, <section>, and <footer>. These elements provide clearer structure to your web pages, making them more accessible and improving search engine optimization (SEO).

2. Lazy Loading: Implement lazy loading for images and videos on your website. This technique delays the loading of non-visible media until the user scrolls to them, reducing the initial page load time.

3. Responsive Images: Utilize HTML5's responsive image features such as the <picture> element and the srcset and sizes attributes. These allow you to serve different images based on the device's screen size and resolution, ensuring that the user receives the appropriate image size for their device.

4. Local Storage: Use the HTML5 Web Storage API to store data locally on the user's browser. This reduces the need for frequent server requests and improves performance by caching data for faster retrieval.

5. Web Workers: HTML5 Web Workers enable parallel processing by running scripts in the background, separate from the main browser thread. This allows time-consuming tasks to be performed without blocking the user interface, leading to a more responsive web application.

6. IndexedDB: IndexedDB is an HTML5 API for client-side storage of structured data. It provides a way to store large amounts of data locally, which can improve performance by reducing the need for server round trips.

7. WebSockets: WebSockets allow for real-time communication between the web browser and the server. By establishing a persistent connection, WebSockets enable efficient data exchange without the need for frequent HTTP requests, resulting in faster and more responsive web applications.

8. Cache Manifest: The HTML5 Cache Manifest feature allows you to specify which files should be cached by the browser, enabling offline access and faster loading times for subsequent visits. By caching static assets, such as CSS, JavaScript, and images, you can reduce the number of network requests.

9. Server-Sent Events: Server-Sent Events (SSE) is an HTML5 feature that enables a unidirectional flow of real-time updates from the server to the client. SSE is more lightweight than other real-time communication techniques like WebSockets, making it suitable for scenarios where you only need server-initiated updates.

10. Web Storage: HTML5 Web Storage provides two mechanisms: localStorage and sessionStorage. These allow you to store data on the client-side, persisting even after the browser is closed (localStorage) or cleared when the session ends (sessionStorage). Storing data locally can reduce server requests and improve performance.

Remember, while HTML5 features can enhance web performance, other factors like efficient server-side coding, optimizing CSS and JavaScript, and minimizing network requests also play a crucial role. It's important to consider a holistic approach to web performance optimization.