You're probably in the first area, which is not demanding at all. The more you play, the heavier the game gets to emulate.
Having AA enabled is wasted FPS, and causes issues with this game.
Keep your IR at x4 for eyecandy or set it to Window Size which is less demanding and usually gives you free FPS.
The reason why your audio stutters is because your FPS is unstable. You should try to keep it at 25FPS.
If you do have a consistent FPS, and you still have the audio issues, try older recommended builds or check out the wiki.
You could try to overclock your CPU a bit, say 3.5GHz or so if possible. I'd recommend something closer to 4GHz though.
Having AA enabled is wasted FPS, and causes issues with this game.
Keep your IR at x4 for eyecandy or set it to Window Size which is less demanding and usually gives you free FPS.
The reason why your audio stutters is because your FPS is unstable. You should try to keep it at 25FPS.
If you do have a consistent FPS, and you still have the audio issues, try older recommended builds or check out the wiki.
You could try to overclock your CPU a bit, say 3.5GHz or so if possible. I'd recommend something closer to 4GHz though.