Our pal Jamie Holly at Intoxination, who often gives us invaluable WordPress assistance, details in a case study how he moved big dog liberal blog Crooks and Liars from WordPress to Drupal, another open source platform.
Chief among the reasons was that WordPress was struggling to handle the load of a site that sometimes gets 230,000 unique visitors and 2,000 comments a day. Holly did a test and found that Drupal could handle eight times the load of WordPress.
In a comment on Americablog Holly says
Since we moved Crooks and Liars over we had a day with over 500,000 page views (over 60,000 an hour) and the servers sat damn near idle.
In the case study, he explains how he did it. The comments there include a gracious note from Matt Mullenweg, founder of WordPress, saying sorry to see you go, then detailing what WordPress recommends for high traffic sites like CNN’s blogs, which run on WordPress.
Both WordPress and Drupal are open source with thriving user communities. Anyone can write a plug-in, tweak the code, or jump in and help out. This is what makes them so powerful and useful.