def fast_iter(context, func, *args, **kwargs):
    """
    http://lxml.de/parsing.html
    Based on Liza Daly's fast_iter
    http://www.ibm.com/developerworks/xml/library/x-hiperfparse/
    See also http://effbot.org/zone/element-iterparse.htm
    """
for event, elem in context:
    func(elem, *args, **kwargs)
elem.clear()
for ancestor in elem.xpath('ancestor-or-self::*'):
    while ancestor.getprevious() is not None:
        del ancestor.getparent()[0]
del context

def process_element(elem):
    print(elem.xpath('description/text( )'))
context = etree.iterparse(MYFILE, tag='item')
fast_iter(context, process_element)
Using Python Iterparse For Large XML Files