I have normally it disabled
I recommend leaving it enabled.
The thing with "crackling sound" issues is that almost all of them are caused by poor performances, and the few that aren't are usually reproducible consistently and will last for more than a few seconds.
I got perfectly normal sound here using your savestate.
Did you check your cpu usage in your task manager ?
Edit : spacefb, it seems something is preventing rapid fire, it even happens with "physical" auto-fire (my controller has an auto-fire setting), it might be that the game is deliberately refusing rapid fire ?