Completely unrelated story: I bought a red cabbage last week and was so glad to have found a relatively small one in the shop.
…I have been eating red cabbage for the past three days and still have enough left for another two days. Just why is it so damn compressed? I can cut off the tiniest slice from that cabbage and it still fills a whole plate.
Hmm, yeah, it is a bit surprising to me, too, especially for an audio issue, but it’s always possible that you had some weird configuration values in about:config for historic reasons and now some new code, that came in with a Firefox update, isn’t working with that configuration.
Either way, it happens often enough that Mozilla has a troubleshooting routine for it, too, namely refreshing your profile.
If I remember correctly, it places your old profile data into a folder in your Desktop folder. But you can also separately backup your profile by closing Firefox and then copying
~/.mozilla/firefox/
onto an external hard drive or such.