Time to Interactive (TTI)

TTI is a critical indicator of a website or application's overall user experience, as it reflects how quickly users can meaningfully engage with the content on the page.

A faster TTI contributes to a more enjoyable and seamless user experience. To provide a good user experience, Google suggests sites should strive to have a TTI of less than 5 seconds when tested on average mobile hardware.

Improving Time to Interactive can be achieved through various optimization techniques including:

1. Optimize JavaScript execution: Heavy JavaScript execution can significantly impact TTI. To optimize it, minimize the use of long-running tasks by breaking them into smaller chunks, defer the parsing and execution of non-critical JavaScript, and utilize Web Workers to offload computationally expensive tasks.
2. Code splitting and lazy loading: Implement code splitting and lazy loading techniques to only load JavaScript modules when they are needed. This reduces the amount of JavaScript that needs to be parsed and executed, improving TTI.
3. Minimize render-blocking resources: Render-blocking resources, such as synchronous JavaScript and non-critical CSS, can delay TTI. Inline critical CSS, use async and defer attributes for non-critical JavaScript, and eliminate unnecessary blocking resources.
4. Optimize critical rendering path: The critical rendering path is the sequence of steps a browser takes to process and render the first content on a page. Optimizing it, by minimizing render-blocking resources and reducing file sizes, can help improve TTI.
5. Prioritize visible content: Prioritize rendering the content visible on the screen (above-the-fold) and defer the rendering of off-screen content. Techniques like lazy loading and content placeholders can help achieve this.
6. Optimize CSS: Heavy CSS can impact TTI due to the time required for style calculations and layout. Minimize the complexity of your CSS selectors, avoid using expensive CSS properties, and remove unused styles to optimize rendering performance.
7. Reduce server response time: A faster server response can help improve TTI by reducing the time it takes for a server to deliver the HTML document. Optimize server configurations, use a Content Delivery Network (CDN), and implement caching strategies to minimize server response time.
8. Leverage browser caching: Cache static resources, such as images, stylesheets, and scripts, to decrease load times for repeat visits and improve TTI.

These are just a couple of suggestions on optimizing your TTI results. Get into performance-first mindset with our comprehensive frontend performance checklist.

Continuously monitor and analyze your website's performance to identify areas for improvement and maintain a high-performing site.