Time to Interactive (TTI)

TTI measures how long it takes a page to become interactive -- displaying suitable content, event handlers become recorded for detectable elements and whether the page responds quickly to user interactions.

Oftentimes, sites will sacrifice quick interactivity in order to bump up visuals, which can make for a frustrating user experience.

Speeding up load speed to interactivity

Delaying or eliminating unnecessary JavaScript code that executes during page load is a start. This can be done with Tree Shaking and Code Splitting among other things.