To make my extranet web application even faster/more scalable I think of using some of the caching mechanisms. For some of the pages we'll use HTML caching, please ignore that technique for this question.

E.g.: at some point in time 2500 managers will simultaneously login on our application
(most of them with the same Account/Project)

I think of storing an Account-cachekey and Project-cachekey into the user's Session and use that to get the item from the Cache.

I could have simply stored the Account into the session, but that would result in 2500 of the same Accounts in memory.

Is there a better solution to this or does it make sense :)?