I don't have a reference for this, but when it's come up in the past they've said size is not a primary goal for the project. A lot of the size comes from their internal event system that normalizes events cross-browser along with the extra abstraction for pluggable renderers (i.e. support React Native) and the component-local state handling. None of these are necessary to get the virutal dom model working. Finally, 132k minified is 40k after gzip. It's not THAT large but it's not a lightweight framework either.