Try switching off the 3d-sound. It was the major slowdown on our game.

(Maybe someone can affirm my observation: in FarCry the voices of the enemies don't sound 3d to me. Did they have the same problem within their engine?)

http://www.puppenheim.org/
http://www.wuerfels-welt.de
Old Game Tutorial: http://www.puppenheim.org/MITutorial.zip
Free Game Editor: http://puppenheim.org/AlienalsWeihnachtsmann.zip
http://www.puppenheim.org/blender_starting_main_settings.txt