EFP for huge Userbase

Hi Everyone,

We are actually trying to implement an External Facing Portal for a very huge User Base ie close to 35 million users. Do you think its feasible to open an EFP to such a huge load of users? If yes, what should be the best way to implement it?

I tried going through a lot of threads for this info, but didnt quite manage anything. Please do help me out with this, if someone has some info/experience with this.