Performing load tests with more than 30,000 Virtual Users almost always requires external resources to generate the load. Testing from the Cloud is very useful to provision a large amount of machines. With many Load Generators in the Cloud, it is strongly recommended to use a NeoLoad Controller in the Cloud too, to avoid any networking issues.
For heavy tests fully performed and managed in the Cloud, it may be useful to tune the scenarios to optimize the testing environment, before setting the Cloud Controller and the Cloud Load Generators.