PWA with Ionic 3 with lazy loading


We are developing a PWA using Ionic 3 with lazy loading concept to bring a better initial loading time. The final build size come to around 1.8 MB (main.js, main.css + one root component) in the prod mode. We are trying all the options to bring down the size further to give a better initial load (our target is less than 6 seconds in 2G connection)
One of the option we tried was moving the 1.8MB of (main.js, main.css) out of the final bundle and planning to serve from a CDN. So that we can a give a better initial experience for our 2G customers.

Is there any other optimized way to decrease the final bundle size to less than 1 MB. Please suggest!

Thanks in advance!