This looks kind of neat although I wonder what kind of effect it would have if some user just loaded it onto the production network? I would think it would create quite a bit of replication traffic. But if you are looking to figure out how beefy of a DC you will need at a site, this might help you out.
ADTest is an Active Directory load-generation tool. It allows you to simulate client transactions on the host server. By varying client load, you can relate the transaction rate to resource utilization on the server and get some idea about the requirements for your environment. Because ADTest can perform generic Active Directory requests, it can also create an organizational unit structure inside Active Directory. You can add many organizational units and user objects in those ADTest-created organizational units. You can also add attributes to the user objects. Once you have created the Active Directory structure you require, you can use ADTest to perform various Active Directory requests, including Modify and Search. Several pre-built tests have been written to reproduce some typical activities you might want to evaluate. Examples of these pre-built tests are: an interactive logon, a batch logon, a search for a random user, and a modification of an attribute of a random user. By varying your hardware environment or other test parameters, you can gain insight into the performance sensitivities of your particular setup.