[untog]

I'm not so sure I agree there. Not that React isn't fantastic, but I remember a recent release adding support for SVG elements. If I don't use any, it would be great to strip out that functionality - React is not a small library. Alternatives like Preact show that you can have a core set of functionality at a much smaller size.

With the prevalence of npm and mini-libraries I'd be interested to see if the size of React could be cut down and put into optional components.

[Klathmon]

Have there been any efforts to have tree shaking work with react?

It's not a magic bullet, but it can go a long way in helping remove a ton of unused-for-your-use-case code in your production build.

[lhorie]

I don't think tree shaking would help much. Speaking as an author of one of those mini-virtual-dom libraries, from my experience/research, the choices of features to support are usually tightly integrated for performance reasons.

For tree shaking to work, it must be possible to statically infer that some code is not part of the dependency graph of your application. Something like SVG support requires extensions to the virtual dom node structure that the renderer's visitor looks at, so it's quite difficult to make it into a hook and not lose performance to various overheads. It's also worth mentioning that over-modularizing can get boilerplatey (e.g. https://github.com/paldepind/snabbdom#inline-example)