[jordow]

Hi, I'm Jordan a member of the React core team.

React is only 32kb(gzipped) in the production build (which also has performance optimizations that the development build does not).

We've also found that React helps make the rest of your application code much smaller, which may end up being even more important - but 32kb is certainly reasonable. We're extremely conscientious of page load speed and performance at Facebook which is why we place so much emphasis on React performance - second only to correctness and proper abstraction.