We have made some slight changes to those worlds that have been designated as themed worlds. This is because themed activities were causing lag on certain servers, while they weren't on others; some servers are simply much more able to cope with hundreds of people all crowded together into one Castle Wars game, for example.
With this in mind, it makes sense to move a few of our server themes onto worlds that can cope with the levels of activity.
Our first choice was always to select worlds that players had unofficially chosen for an activity and, where possible, we have tried to keep these activities on their chosen servers. The reduction of lag on a world, we now realise, is far more important - particularly if that world cannot cope with large numbers playing something server-intensive like Pest Control.