We’ve turned off uglifyjs because it takes a lot of time and resources to build our app. With this change, we could reduce our “app.js” bundle size from 1100 KB to 600KB. That’s a pretty neat improvement.
Faster, Leaner and Better Next.js
Arunoda Susiripala

I don’t get this part. How did you reduce the size of the bundle with disabled minification?

I checked linked github issue and I understood using already minified version of React by wepback alias but still it’s hard for me to see how this could change the size of the bundle so dramatically.