Does each apache process load all DocumentRoot's for all virtual hosts?

we are trying to diagnose a performance issue. We have an Apache2 server with many virtual hosts, each one running a CMS such as Drupal or Joomla. Each apache process seems to consume a large amount of memory. Is there any way to see what it's loading into memory? Does each apache process load all the files from each DocumentRoot into memory, or only the file开发者_如何学Gos for the DocumentRoot corresponding to the virtual host it's serving?