Correct if you set that option to YES you are telling our program when we update the category photo and comment counts for the members gallery to scan the entire table.
Therefore if you set it to NO then it will only scan a count from category 500 which is the members gallery
It is all about options. Here are some other tidbits to turn off to save processing
http://www.photopost.com/forum/showt...38#post1113838