Clarify scaling impact

In a conversation with James Cramer, some concerns was raised with regards to how this impacts scaling:

My only thought is there is not any mention of potential scaling or scalability impacts. Impact on db IO times? Impact on disk/ram storage from new any new data structures required?

Maybe these should be placed in "Costs & Risk Mitigation" but I'm not sure.

I think it's valid concerns and that we should document this so that there's no uncertainty about the scaling impact.