This example app demonstrates how a landing page can help improve a Flutter Web app's perceived loading time. The landing page, including this text you are reading, is written using plain HTML and JavaScript. It loads instantly as it does not require any extra runtime. The JavaScript is minimal, and the browser already has the HTML engine warmed up and ready.
While the user is reading this text and familiarizing themselves with the app, the app is being loaded in the background. On a typical modern internet connection the Flutter app only takes a couple of seconds to load, but there could be rare situations when the connection is flaky or slow, which can stretch the loading time. Hopefully, by the time the user is done reading and is ready to hit the "Start" button, most (if not all) of the loading process will be finished, and the app starts instantly. Alternatively, additional start-up UX, such as a loading indicator can be used if the app hasn't loaded before the user clicks the start button.