A recent PR (ipython/ipython#7757) into IPython adds binary comms so that we do not have to launder pngs through a base64 encoding to communicate with the JS side.

We should look into using the binary comms to see if we can get a bit more performance out of nbagg.

Not sure on what timeline we should aim for here as this is not in a released version of IPython/Jupyter (as of 2015-04).

attn @pelson