Warn on performing /list
Performing /list on big networks can have not-that-great results like keeping the core busy for a long while (writing the channel list into the database) and disconnecting clients during this time.
Also it might not be desirable to have several thousand channels listed in the backlog/database.
This is especially annoying if one is used to other clients' /list #channel to display channel topics etc. and either Quassel doesn't support this and displays the complete list instead (?) or one accidentally omits the channel argument.
Maybe you could move /list to /list networkname and display a note when the user performs /list.
Not optimal and perhaps not following the specifications, but it might be worth it in this case.
(Waiting for ten minutes until the core responds again is... not fun ;) )