Happens in both latest dev branch and RC (1.56.134551)
If I fire off around 5-10 rounds, any successive rounds don't make any audio, instead it gets buffered and all the sounds play instantly together after a few seconds.
I've tried changing the audio quality from 48000 Hz 24-bit to 44100 Hz, 16-bit. This changed nothing
Hitting escape and pausing the game seem to play all the buffered sounds.
Changing the amount of sound sources (I tried 128 and 64) have no noticeable effect.