I'm not sure that's accurate.. I've been using Browserify for some time, and write code like that pretty much all over (require('../lib/api'), require('./api'),

I'm not sure that's accurate.. I've been using Browserify for some time, and write code like that pretty much all over (require('../lib/api'), require('./api'), etc.) without having file duplication issues in the bundled output. Do you have an example that exhibits the problem? Also, if you're requiring large files that you know won't need processing by browserify (like react), you can use the 'noparse' option to prevent the performance hit during bundling. (Of course a cdn is potentially a better option.)