If you have created your site using Drupal and are experiencing high load or CPU issues we recommend you have a read of the Drupal forums http://drupal.org/forum. These forums contain numerous bits of advice from others who have similar issues with Drupal installations.
Other specific examples:
Installing the modules found here http://groups.drupal.org/node/2623 can often reduce your CPU and is a good place to start.
If you believe your account was hacked;