If there’s no indexed attributes in your query, AD’s going to crawl the whole DIT to search for results (every time!). Help AD be more efficient by either including an indexed attribute in your search filter or indexing an attribute that’s part of your search that currently isn’t indexed. Including an already indexed attribute to your search is probably your best bet here. If you’re searching for users or contacts, try to include that in your search filter ( &(objectClass=user)(objectCategory=person) ). Don’t search for attributes that have little entropy. If 80% of the objects in your directory have a value in attribute x, it’s not worth filtering (x=*). If you’re attribute only has a couple of possible state (preferredHand=left) where only “left” and “right” are possible values, including that attribute to the filter might not shrink the search base noticably.