I hear clicks whenever the volume of some audio stream is adjusted
Solution 1:
You may be hitting latency limits of your hardware when pulse is "busy".
configuration: driver=snd_hda_intel latency=0
There is really no such thing as zero latency. I presume that means sub-millisecond.
Per this https://arunraghavan.net/2013/08/pulseaudio-4-0-and-skype/ Setting the env variable PULSE_LATENCY_MSEC=10 before starting an app. This gives the software 10ms of buffer time if it has more work to do mixing streams.
10ms is still low enough latency unless you are playing live music digital instruments or very fast games.