It's probably something to do with how these apps communicate with the audio. There is obviously multiple ways since some things can go silent, and other not, when you put your phone into silent mode..

The original developer of pianobar sent me a note that by simply changing drivers on the computer and using OSS instead of ALSA there was a rather dramatic decrease in overhead and memory. (It's already very small, but even smaller with those changes).. so evidently there's some impact also regarding audio drivers and what underlying audio system is used.

But still.. I'm unable to test, verify, or fix any of this at this time.