Better website performance, access to better and more features, are the couple of primary reasons stated to migrate websites from Drupal 5.x to Drupal 6.x. While the process sounds simple enough, it is fraught with performance issues that contributed Drupal 6 modules bring with it - specifically on high-traffic websites. Srijan has worked on quite a few D5 to D6 upgrade projects, such as the one for Enough.