TopoJSON files are often smaller than GeoJSON and the conversion allows you to incrementally simplify a dataset, if you wish.
Glad you asked, oh handsome OP.
From the command line (Mac OSX 10.8, assumes homebrew installed):
brew install node.js npm install -g topojson
Convert The Data
topojson -o output.json input.json
If you feel better with Python, just install the library by running:
pip install pytopojson
And then run:
python geo2topo.py geojson_file
You can also use a quantization parameter. Just use the
-h argument to see how it works.
Let me know if this was helpful to you!