title: Python: words replacing in huge text
body: <p>I have a huge text and a list of words ~10K. 
  What is the fastest way in Python to replace all this words in text with some other word?</p>
  
  <p>EDIT: 
  Text size >1Gb, text is human written, and "extremely tokenized" (any runs of alphanumeric characters and any other single symbols was splitted into new tokens)</p>
  
  <p>a number of words >10K, each word frequency in text is 1
  the replacement word is same in all replacements.
  Python 2.5-2.7</p>