Seamonkey is based on the same code as Firefox, so chances are it will have the same problem sooner or later. Also, it's a fairly heavy-weight application.

Seamonkey?

try Archbang (live CD) - Arch based, CrunchBang inspired, very minimal distro (openbox+panel+web browser+file manager+terminal)

maybe to record playback in audacity without jack (eg. sampling from youtube clips)

yeah, the Red Hat / Lennart Poettering conspiracy (pulseaudio, systemd...) is slowing tainting and destroying the free software / unix ecosystem, piece by piece

For all you pulseaudio haters out there (so, myself included, as well as pretty much any other Linux musician I know) I have some bad news: Starting with the upcoming ESR, Firefox will depend on pulseaudio. Not sure how to deal with this, things are looking pretty bleak as far as browser alternatives are concerned. Palemoon is build on legacy code, so probably not exactly secure, and Chromium is even slower than FF from what I hear, plus it doesn't have a good mechanism for selectively blocking scripts.

First thing I always do is disable/unistall pulseaudio. No idea why I would want to use pulseaudio in the first place, always just gave me issues.
I am now running Ubuntu Studio on an old eeepc (I think a 1000 series) and it runs ok, apart from the really horrible latency (anything below 512 samples will give me lots of xruns) even after running RTIRQ. But apart fromt that it works fine for the things I need to do with it.

People keep telling me to install Arch, which is a bit of work... so I never really get to try that. But a lot of people swear by it, and it has the advantage of not coming with a lot of useless stuff you don't want installed by default.

I think I've found a solution, it seems if I run JACK, with pulseaudio bridged to jack, I don't have this sound problem. So I think I'll be able to work again on Beepola!

you could  try to reinstall alsa but anyway I hope you are happy with fedora.

I was not able to watch youtube and launch another audio apps at the same time ( both alsa client ).
If I use on this setup two audio jack compatible apps it works.
So seem to me a dmix problem, but it was a really modified debian with a lot of tweak, so I think I have just broke the alsa configuration file...

hold on.
are you talking about music production/audio recording apps? if so, in most cases you will need jack (but not pulseaudio!).
but if you simply can't hear playback from mp3, youtube, video at the same time (dmix) - there is something wrong with your setup.

Wahoo, so it's only me i think...

well I have similar setup:
Core2 Duo laptop 4GB RAM debian unstable with latest kernel, openbox wm.

Nothing about hardware I think in my case.
IMHO, it's only kernel related and packaging.
I use a hp laptop pavillon g6 amd 2 core with 4g of ram with debian unstable with the lastest kernel available.
I've switch to fedora 25 this week because I'd like to have a distro oriented desktop not a custom fluxbox wm anymore.

unless you use digital output or run distro from previous decade, it should work fine, no need to configure.  dmix was enabled in alsa...  10 years ago?

what's your hardware?