Well, essentially, every time I turn on sound (3D Sound disabled even), and for example, thrust, or hear several weapons firing, framerate goes down, in timing with each sound.
Is it a problem with my computer, or my installation of Freelancer, or my graphics or sound card?
I have it too. But my PC is a frankenstein monster and my sound card was manufactured in 1999. I looked up Tech Support online and got the "End of Service Life" message.
I play with sound off, but music and voice on. The only drawback is if I'm in a transport/cap and a bomber fires a SN at me out of my FOV, the only way I know I'm being shot at is if I see it being fired.