[chrismorgan]

I imagine that accidental unfair scheduling is to blame here: that the audio processor is keeping things busy in such a way that Firefox isn’t getting its “hey, this tab is closed” message through to kill the event loop. This is definitely a bug in Firefox, and it appears to be consistent across platforms (I’m on Windows, you’re on macOS, someone else is mentioning Android). The patch to fix this is likely to be quite small.

[PaulDavisThe1st]

I do notice, that PulseAudio shows me that the audio stream from Firefox is labelled "AudioCallbackDriver", which is unusual: most Firefox audio streams are labelled "AudioStream". I think this is a little-tested feature in Firefox at this point. Somehow it also manages to activate the speech (espeak) dispatcher too.

Not cool.