what does it do? alls i know is it takes forever when i compile my map. (half hour maybe).  if i were to perhaps ctrl alt delete it and end task....would it dramatically effect my map?  Bear in mind that I am currently using the compile tool to test my map....im not done with it.  I also know about the visgroups and cordon bounds and whatever. Just wanna know if i should be goin around ctrlaltdeletin this task....cause its takin for-freaking-ever.