Wouldnt it be nice to have a export file which is free from unused code?
I mean in the bootstrap framework is so much unused css and jscript code, which you dont need.
That would be an outstanding feature!
See for example this: https://uncss-online.com/
I agree 1000% !
Making websites responsive to a device's viewport size is one of the main advantages of Bootstrap. But without minimizing the CSS & JS folders a web page viewed on a small device will always be slow - and often even jam.
Removing all unused CSS & JS can cut library sizes to 10% of the full size. This means the average search time for CSS/JS components cut by 90% . . . . . . which is a vital gain for viewing on mobile devices.
That's not how the web works. Linking to external bootstrap and jquery libraries in your site does NOT mean that the user has to download those files. They are probably already cached (until expire time) from other navigation sessions.
Usually images are what use (and waste) most KB. If you have to optimize something start using srcset and picture attributes to serve smaller (and art directed cuts) to users with smaller screens. And of course optimize to death every single image and logo you use in your design.
The drag/drop effect of heavy BS libraries on websites viewed on small mobile devices is well reported.
http://ubwg.net/b/removing-unnecessary-css-with-uncss
It is not a question of space lost by downloading everything. It is a question of time lost while searching through remote libraries 10 times bigger than needed through holding redundant styles or scripts.
Caching requires the remote material to be successfully downloaded to the mobile device previously. While some users will be lucky - or patient - enough to do this, many others may fail or give up. Especially if it's the first time they have tried to open that website.
Effective web apps have to consider their likely users' resources, i.e. device CPU and available time, if they want to generate customers.