Faster CSV to GeoJSON that only supports node.js and streams.
It's less user-friendly, not available as a library, not compatible with browsers, but also a lot faster.
npm install -g csv3geojson
csv3geojson takes input from stdin, outputs into stdout, and takes two parameters, the names of the longitude and latitude columns.
~/src/csv3geojson〉time ./csv3geojson LON LAT < ~/Downloads/us/va/statewide.csv > statewide.geojson
./csv3geojson LON LAT < ~/Downloads/us/va/statewide.csv > statewide.geojson 63.35s user 9.62s system 95% cpu 1:16.32 total