it's a decent idea, keep them coming. Any ways you can think of that will speed the site up are good and I'm sure will be taken into consideration. Personally, I don't see this as being too practical. Users are always going on and offline and I like how it is constantly updated each time you visit a page. Even if the list was refreshed every 5 minutes instead, I don't see it as saving that much time. The list is plain text - there's no large image files, sound, or video clips that slow it down too much. Right now, the whole list can't be more than a few kilobytes.
Eat. Sleep. Breathe. Ski.