Can MODx handle 7000+ simultaneous user sessions?

I am creating a prototype application for a large organisation that will likely have at least 7000 concurrent users. It is a relatively simple app and I am hoping to leverage MODx for authentication. I saw MODx is expected to be able to handle many thousand registered users although having so many open sessions may not be so easy.

Anyone put together anything similar, dealt with the load balancing required to get this thing working properly with MODx Revo?

What considerations do I need to have with such a large active users table/session folder?

There shouldn't be a problem with MODX supporting 7k concurrent users, however, your server supporting 7k concurrent users will be the bigger question.

Also, just to clarify some, is this 7k users all logged in at the same thing all doing stuff at the same time (in a MODx website), or just 7k users who will be logged in, but not all doing stuff at the same time. Basically, will the server be serving 7k requests at the same time, or will they be spread out a tad?

Also are you looking to just use MODX for the authentication, or for the entire site?

Handling 7000 user sessions is not an issue in and of itself. Handling 7000 requests per second however would be and you would indeed need a load-balanced configuration tailored to your needs in order to handle that, with lots of nodes. A typical web server node with Revolution can handle only a small portion of 7000 requests per second depending on the caching strategies, database configurations, the weight of the requests and the configuration of the hardware.