There are basically two types of vandalism -- manual and automated. Because this wiki is regularly maintained and Admins frequently check the Special:RecentChanges, manual vandalism typically gets taken care of very quickly. What we are more concerned about is vandalism automated by vandalbots. A vandalbot is a script which automatically performs some kind of edit or similar operation to the wiki. Because of the speed with which they work, they can do a lot of damage, and this damage can take time to fix. It is a sad fact that as our traffic and popularity has increased so have the automated attacks.