I'm using a SessionListener to check if a user is online or not.
It basically keeps a List of all online users.
Too check if one is online or not I use "contains()".
If there were say a few 1000 users online it would take a while to perform "contains()".
That's why I thought of splitting up the lists in a few lists identified by the first 3 chars or so of the users id.
Is this the way to go, or are there other, better ways of doing this?