One thing to do in order to reduce the bundle size is to import only the required components from a library and not the COMPLETE library.
Example of COMPLETE library import:
import { FlatButton } from 'material-ui';
Replace it with the component import:
import FlatButton from 'material-ui/lib/flat-button';
This way, you'll only import what you need each time. Try to do this for every library :)
Also, I found this, but I did not try it at the moment: github.com/robertknight/webpack-bundle-size-analy…
This may gives you some insight on how to reduce your bundle size.
Satyanarayan Dash
Front end Lead at Happay