Time to Interactive, or TTI, as we mentioned in the previous section, is one of the six metrics that are tracked in the Performance section of the Lighthouse report used for tracking overall web page load speed. Time to Interactive marks when the page loads to the point where the page is read for the user to begin interacting with the page. Even though the Time to Interactive only makes up 10 percent of the weight of the Performance score, it is a key factor in terms of providing a solid user experience. The longer it takes your site to become interactive, or if content appears that it is ready but shifts as the page is loaded, it is going to frustrate visitors.
To a user it may seem that your site is unresponsive, or broken, and they may end up bouncing from your page if they cannot begin scrolling, clicking, etc. Worse yet, this delay can be more noticeable on mobile devices, where user’s network connection can also impact the length of time it takes the page to become interactive. You may have even experienced this frustration yourself on pages you have visited. The first thought you have is probably that it is not your connection that is causing the page to be slow, it is the website. Although, what is more likely, is that it is a combination of two. As a website developer, you must ensure the resources on your side are optimized as completely as possible, so that your resources are not the reason for potential performance bottlenecks.