Mr. SD has mentioned that he's insterested in speeding up the forums. Displaying the active users can't be making the forum work any faster, and I doubt that many people actually use the feature often. Too, some users are "hidden," so their names don't appear on the list.
I'd like to have the option to hide it, if possible.
At this instant (I checked) the active user display list takes about 35,000 characters. The list includes hypertext links to user profiles, so it's not just the names that are downloaded, it's the links, too. (Each link looks like: <a href="member.php?u=5258" rel="nofollow">rayzac99</a>).
On a dialup line, that adds between 5 and 10 seconds every time the active user list is loaded or refreshed. Those of us who have access to plenty of bandwidth won't notice delay, but dial users are indeed affected.
Also, the list takes up valuable screen space.