Portaudio is known to produce great latency in some cases...
Portaudio indicates the best possible latency based on the sound card.
The actual latency depends on the backend audio APIs used by Portaudio (which you can choose) and of course on the application that uses it.
For example, GTK eats latency, Qt is much better (and MSEgui is the best

).
I think that new Kubuntu 24.10 do not come with Portaudio
Did you install
Audacity? It uses Portaudio.
[EDIT] Could it be that you're confusing
PortAudio with
PulseAudio?
PipeWire does indeed seem to be an alternative to
PulseAudio.
And a "X11/Wayland-style" battle is raging.
That's why I love
PortAudio, which lets you choose the API installed on the system.