At what point do you expect a loss of performance due to too many indices to be managed?

Since iCAS does not use a database, there is no need to manage indices. That means there is neither a restriction of the number of containers nor is there any performance loss if many containers exist. The containers themselves keep the information about the contained data, so no global storage, e.g. a database, is needed.
The only impact is a slower transfer rate if the number of container identifiers increases significantly. This does not affect a restricted query, such as a certain month or day.