The application cache allows users to access websites and applications while offline. The benefit is that users can access them while offline and there is no requirement for network connectivity. Additionally, because the user is accessing resources cached in the browser, they load faster. One of the caveats with the application cache is that, if not configured properly, the browser would continue to serve the cached version, even if the server were updated.
Use an Application Cache (Deprecated)
What is the Application Cache?
Why was the Application Cache Deprecated?
Lighthouse is an open-source tool that is used to run an audit against your web pages and provides scores and suggestions for improving page performance, accessibility, SEO, and more.
PageSpeed Insights is a tool created by Google that reports on the performance of a page on both mobile and desktop devices, and provides suggestions on how that page may be improved.