Drupal users have high satisfaction with Drupal compared to the Joomla users, for a number of reasons. If you are thinking of  choosing a high performance platform to run your high traffic website.. Drupal Installation is your forte!

Overload Scenario
Drupal is scalable high performance CMS and is stable under heavy load. If your server is pushed beyond its capacity, Drupal shuts off gracefully and doesn’t crash. As soon as the server is back within its traffic capability, Drupal handles all requests smoothly again. For example if your dedicated server can handle a maximum of 50,000 visits a day, and on lucky days when your news created the buzz in social media and your traffic rose to 70,000 on one day, then your server will be overloaded and usually it crashes causing permanent damage to your database at times.. But if you have used Drupal CMS it closes down gracefully an as soon as traffic goes down to within the server’s capacity, the Drupal running site accepts all requests again.

Extensibility
Drupal users know that their add-ons integrate better with the core, and their framework makes it easier to extend their CMS’s capabilities..

which makes an extended version of it quite stable unlike Joomla, which loses its strength if you have plenty of plugins & heavy customizations running. Any CMS with number of plugins makes the content complex and reduces your ability to handle high traffic requests.

Accessibility Management or ACL
Chances are if you are high traffic website, you may have various users & content contributors. ACL means group roles that is assigning people out of the various registered user levels and allocating many kinds of privileges. The most common example is the ability to see or edit a section or selected pages. This efficient feature of Drupal makes it a class apart than other CMSs out there.