Not being a dev writing code running in realtime nor an audio type with experience of things not running in realtime, what happens when GC kicks in? Does the entire audio stack go silent? Does it only effect the one filter so it sounds like a drop, or is it a pause so not it is no longer in sync? In theory, I get why it is bad, but I'm curious of what it sounds like when it does go bad.
Python mainly uses reference counting for garbage collction, and the reference cycle breaking full-program gc can be manually controlled.
For RC, each "kick in" of the GC is usually small amount of work, triggered by the reference count of an object going to 0. In this program's case I'd guess you don't hear any artifacts.
The audio interface hardware expects to get N samples every M msecs, and stops for no man (or program). So, anything that stops or flows the flow enough that less than N samples are delivered every M msecs causes a click or pop in the output. How bad the pop actually sounds depends on a lot of different things, so its hard to predict.
