title: Upgrading from Drupal to Pressflow
body: <p>I have drupal based website (Drupal version is 6.19), it is very heavy content website (about 400K articles in it).  </p>
  
  <p>By following Rule one of using Drupal, <b>I didnt make any change on the core</b>. but i have a lot of enabled modules and some of them were customized.  </p>
  
  <p>Now, I am suffering of the performace and I need to enhance it. I never used Pressflow before, but I have read some articles saying that pressflow is better than Drupal. is it safe to upgrade from Drupal to Pressflow? and if so, how to do it?  </p>
  
  <p>Thanks for your help</p>