Official material-ui github repo gives an example how to integrate material-ui with next.js - nextjs/pages/_document.js

In this example styles generated in getInitialProps, but it's not the best way due to performance reasons:

1. getInitialProps enables server-side rendering and can't be statically optimized. In this case it runs every time we open a page.
2. It causes issues with Vercel hosting - cold start sometimes takes 5-10 seconds and user just see white screen.

It isn't possible to just replace getInitialProps by getStaticProps because getStaticProps doesn't work in /pages/_document.js and /pages/_app.js files.

Does anyone solved this issue?