Rockstar in their continued support for Grand Theft Auto IV on the PC, have released update 1.0.4.0. However, this isn't a full fleged update but rather a maintenance update. This update is only really for bringing the game in-line with the new retail disc pressing (that means that new retail copies are now going to include all the patches so far), however, Rockstar Toronto did mention that this update does have updates to the resource management numbers which should improve performace for some.

Download: Update 1.0.4.0