To a user, the startup latency of an HTML 5 based application is critical, because thats the first impression of app's performance. If it's really slow, they might not even bother to wait for the app to load before navigating away. Even if your application is blazing fast after it loads, the user may never get the chance to experience it. There’re several aspects that contribute to startup latency: 1. Network time to fetch the application (JavaScript + HTML) 2. JavaScript parse time 3. Code execution time to fetch the data and render the home page of your application. The third issue is up to you! The first two issues, however, are directly correlated with the size of the application.

Full Article: Code Blog