TurnKey Moodle uses the unmodified upstream source. Regarding scalability, you can get quite a bit out of mileage on a single instance, even a small one, but how far really depends on the specifics of your usage scenario. The best way to find out is to test the performance using web benchmarking tools that simulate users.
Also, we'll be introducing support for larger instance sizes soon so when you need to grow out of the small instance you'll be able to do that.
But 10,000 users all active at the same time is a crazy load. If those 10,000 users are active for an average of 5 minute sessions across the day that is roughly equivalent to 3 million active sessions per day and about 50-100 million visits a month.
It's very rare for any website to reach this scale. There are probably not more than one thousand in the world that do. Usually complex cluster configurations are needed to support it.
10,000 simultaneous users = 50 million visits a month.
Also, we'll be introducing support for larger instance sizes soon so when you need to grow out of the small instance you'll be able to do that.
But 10,000 users all active at the same time is a crazy load. If those 10,000 users are active for an average of 5 minute sessions across the day that is roughly equivalent to 3 million active sessions per day and about 50-100 million visits a month.
It's very rare for any website to reach this scale. There are probably not more than one thousand in the world that do. Usually complex cluster configurations are needed to support it.