In comments on this performance audit of a React site, the lodash author suggests "cherry-picking" methods in lodash (i.e., requireing individual methods instead of the whole lodash package) or using the individual packages. But shouldn't this be unnecessary if using a dead code eliminator such as uglify or the closure compiler as part of the bundling process (using browserify or webpack)?
If you are using CommonJS style require('lodash'), Uglify doesn't dead code eliminate (I don't think Closure Compiler will be able to either).
However, if you are using ES6 style import { merge, reduce } from 'lodash' (for example), you will be able to take advantage of tree-shaking using Webpack2 (some other bundlers support it, too). Since ES6 module system has a static structure, the bundler can perform static analysis and determine that certain parts of library are not used and eliminate them.
For more information about tree-shaking with Webpack 2, you can take a look at http://www.2ality.com/2015/12/webpack-tree-shaking.html.
As of writing this answer (March 3, 2016), Webpack 2 is still in beta, so there may be some issues but if you'd like to experiment, give it a try!