Time to interactive

Time to Interactive (TTI) is a non-standardized web performance 'progress' metric defined as the point in time when the last Long Task finished and was followed by 5 seconds of network and main thread inactivity.

TTI, proposed by the Web Incubator Community Group in 2018, is intended to provide a metric that describes when a page or application contains useful content and the main thread is idle and free to respond to user interactions, including having event handlers registered.

Caveat

TTI is derived by leveraging information from the Long Tasks API. Although available in some performance monitoring tools, TTI is not a part of any official web specification at the time of writing.

See also