ipython/ipython — pull request #5576 by minrk (2014-04-10 05:08:52+00:00)
Title: only process cr if it's found

because re.sub is crazy slow.

I found [a notebook](https://github.com/pysal/pPysal/blob/master/weights/two_stage.ipynb) that takes about a minute to render in master, and 2s with this PR.

I think this is why nbviewer is still having issues, so I think we should merge this ASAP.