The cElementTree module is a C implementation of the ElementTree API.
On typical documents, it's 15-20 times faster than the Python version
of ElementTree, and uses 2-5 times less memory. On modern hardware,
that means that documents in the 50-100 megabyte range can be manipulated
in memory, and that documents in the 0-1 megabyte range load in zero
time (0.0 seconds). This allows you to drastically simplify many kinds
of XML applications.

Author: Fredrik Lundh
WWW: http://effbot.org/zone/celementtree.html