Each of our $1 wordpress themes provides test data for free, to all of our members, on their shop pages.
For testing, i suggest having a developer input data into the database. Very few servers will allow a million records to be uploaded through a form.
Once that’s done, i recommend using any of the popular load test and/or stress test tools available via google. Many allow free testing up to a limit of users. They often provide detailed data regarding each virtual user that they send to your site. With that type of info, you would have exact metrics regarding how many concurrent users it takes to break the plugin on your server
BePro Software Team