Chrome on Android's Data Saver feature shows when a page is optimised, and reduces data use by up to 90%, helping pages load faster.

To show users when a page has been optimized, Chrome now shows in the URL bar that a Lite version of the page is being displayed. Users can tap this indicator to see more information and to access an option to load the original version of the page. Chrome automatically disables Lite pages on a per-site or per-user basis when it detects that users frequently opt to load the original page.

[blog.chromium.org...]