Dojo out of the box is not really efficient, there are some optimization to do before putting it in production :

• Build it (Dojo Doc)
  • On command line as explain in Dojo Doc
  • With an Eclipse Plugin
  • With an
• Optimize your Dojo Application as describe in the Dojo Book

You can also read this very interesting article from Eugene Lazutkin about Dojo Application Optimization.