Hi,this numbers should not present a problem for AEM, if you have a
Publish farm then SCD would be used to sync the users.I'd be more
interested to understand the use case, will the users simply be logging
into AEM or will their profile be used in some way? By this I mean will
you be storing personal details about the user. If you have an existing
system managing your user profiles then it would be better to integrate
with that, rather than storing details in two places.Regards,Opkar