The audio in the game is increasingly overloading the central processing unit . The problem is aggravated when there are a lot of units and we have to use codecs integrated on motherboards that are "ahem"... horribles.
A great solution to dramatically increase performance would implement support for real-time drivers.
I know they will be thinking that there is no support for this technology beyond sound cards dedicated.
But that's not the case: http://www.asio4all.com/
Right now we support asio even within integrated sound cards: Realtek and others hd codecs.
I see this as a potential future problem since adding occlusion calculations the problem worse.
I do not know how long tardariais to implement something like that but I have an example of open source graphics engine that already has implemented support for these drivers.