Is there any attention towards big performance issues in Ardour on newer distros?

I’ve happily paid for and used Ardour for a couple years now, starting on Kubuntu 23.10 and through Kubuntu 24.04. I’ve written, recorded, mixed, and mastered a handful of metal tracks for my project, all using 20-ish plugins total. I’ve not had any issues with latency (got round-trip to 7-8ms) or xruns on my Scarlett 2i2 with a 128 quantum, 48000 sample rate.

I’ve since moved on from Kubuntu 24.04 and have installed both Fedora 41 and Arch (CachyOS) to trial them both (I use the computer for gaming as well, and these distros ship with newer drivers that support multi-monitor VRR among other things that Kubuntu LTS did not).

On both of these distros, configured as close as possible for audio work as my Kubuntu LTS was, with all recommendations in rtcqs followed, and with the pipewire settings for my Scarlett 2i2 the same (128/48000). The round trip latency measures the same…but unfortunately Ardour is not usable. Even just simple playback of my existing projects results in thousands of xruns, glitchy audio, the the whole Ardour app and playback freezing for seconds at a time. I have to loosen the quantum to 512 to get glitch-free playback. This is in BOTH Fedora and Arch, the same exact issue (but not in Kubuntu LTS).

I re-created one of my projects in Bitwig 5.2, as identically as possible, with the same exact plugins, mix, and even track volume, in a painful effort to determine if this was a distro issue or Ardour. And to my surprise, Bitwig has no such performance issue and happily plays back and records glitch free with the same quantum/rate that causes Ardour to completely fall over.

I’ve left both Fedora 41 and Arch installed to see if this issue ever gets resolved. So far, no. So I’m wondering if this is something that is being looked at? I much prefer Ardour to Bitwig, maybe because I am used to it, but also for the open source philosophy. But the terrible performance is a non-starter.

Are you using pipewire’s JACK emulation on those distros?

So far this is not a known issue. Ardour is known to fine on Arch at least.
There are known issue with pipewire though.

I am using the out-of-the-box setup for all of them. So, full pipewire, and in qpwgraph, Ardour shows up as a JACK app (just like in my Kubuntu LTS setup). As an experiment, I upgraded my Kubuntu LTS to the latest pipewire via the PPA (at the time it was version 1.2.7) and still didn’t see any xrun issue, so there is something else in the newer distros causing it.

What’s tricky is, it seems to work ok in safe mode (no plugins), or with just a couple tracks and plugins. The issue rears it’s head with my full projects (like 20-30 tracks/busses and 20 plugin instances). I’ve tried removing plugins from the project one-by-one and didn’t get any improvements before I gave up.

When my projects play back normally, I am using about ~50% DSP load. This is the same in Ardour and Bitwig. However in Ardour, I notice the DSP and CPU usage sorta freezes during playback/recording, and the DSP usage meter in Ardour tops out at 100%, while CPU usage on the system bottoms-out (goes closer to zero) when it freezes and xruns.

It just seems with Ardour, some interaction with the system is broken causing it to briefly, but constantly “lose” access to the CPU, noticeable at higher DSP load. This does not happen in Bitwig.