GitHub just finished ripping styled-components out of github.com.
Result: 55% less time to server-render a page, 25% faster component init.

CSS-in-JS makes you pay for styles twice: collecting them on the server, running JS on the client.

Static CSS is *always* more efficient.

Ship CSS.

https://github.blog/engineering/architecture-optimization/improving-site-performance-by-shipping-more-css/