Now here is a great find. Guru3D’s user ‘gerardfraser’ decided to try Mafia 2’s apex.dll file and see whether or not he could gain any performance boost with it in Batman: Arkham City. Apparently, there is a nice performance jump as the user witnessed a 20fps boost from using this apex.dll file. In other words, this is a must-have file for those that wanted some of the PhysX effects, but were put off by its atrocious performance.
According to gerardfraser, Mafia 2’s filename disables some apex effects, like papers flying around and some cloth movement effects. Apart from the absence of some effects though, we haven’t experienced any bugs or errors while using it. This workaround works in both DX9 and DX11 and those interested can download this custom apex.dll file from here. All you have to do is place it in ‘X:Steam\steamapps\common\batman2\Binaries\Win32’ and you are good to go.
gerardfraser has also released the following comparison shots between the high PhysX settings of the default apex.dll file and the modified one. The performance boost is quite noticeable, so give it a shot if you are experiencing any performance issues with PhysX.