I use the RPI 3b+ with hifiberry dac+ pro
Sometimes the playback becomes stuttering and the mpd.log shows the Decoder is to slow message.
It happens mostly with tidal master albums/titles.
I tried some cpu governors: also performance, conservative and, on demand showed no difference.
This state is very stable: pause and play changes nothing.
To stop this issue skip to the next or previous title or skipping within the title (forward / back).
I did some monitoring on this issue with tailing volumio.log and mpd.log. I also monitored the cpu with top:
mpd uses 1.5% (tidal), 2.0% (webradio) the stuttering playback only starts on the beginning of a !new! title. The cpu is 97%idle. So the decoder to slow issue comes from the prefetching of the next title. It is independent on cpu time for mpd or volumio (both around 1.5% peak) and it stops when I skip the title (fwd, rev, next, prev).