Embodiments of the present invention address deficiencies of the art in respect to buddy list management for instant messaging systems and provide a novel and non-obvious method, system and computer program product for buddy list pruning for instant messaging system performance enhancement. In one embodiment of the invention, a buddy list pruning method for instant messaging system performance enhancement can include comparing buddy list name entries in a buddy list to entries in a network directory used to authenticate users into a network supporting the instant messaging system. The method further can include characterizing selected ones of the buddy list name entries as either invalid where a buddy list name entry cannot be matched to an entry in the network directory, or as valid where the buddy list name entry can be matched to an entry in the network directory. Finally, the method can include performing presence awareness only on valid buddy list name entries in the buddy list.