Replace "Bush" with "Monkeyboy"

From Chickenfoot Script Repository

Here's my first script, best used at, say, CNN.com or nytimes.com:

// ==UserScript==
// @name Replace Bush with Monkeyboy
// @when Pages Match
// @description replaces bush with monkeyboy in all text nodes
// @include http://www.cnn.com/*
// @include http://www.nytimes.com/*
// ==/UserScript==

  for (word = new find(new TC('word')); 
     word.hasMatch; 
     word = word.next)
  {
    if (word == 'Bush')
      replace(word, "Monkeyboy")
  }

It hogs a lot of CPU though. Is there a way to use a background thread so that Firefox doesn't freeze up during the search?