Unfortunately I do not have nothing special, it is reason why bug report was created as late, because I thought I would find such a exact relationship.
I noticed only one relationship between refresh the list and writing messages. When I send a message then quite often list is updating.
For example (situation from picture), when I sent the next message then the list was updated, but tomreyn was already present when I sent the first message too, because he took it.
... but the problem is quite common and relatively easy to observe it with running at the same time
- an IRC client with lobby channel,
- game client in window mode
in the "rush hour" and comparing for several minutes the both lists of users.
I know that the case is not simple, but maybe someone will add some of his own observations and reveals some kind of relationship which I haven't noticed.