So, I think this might be proof that apple accessibility do indeed read this forum. I had a bit of a meltdown in a post yesterday saying how sending reports to apple accessibility felt like screaming into a void, or something similarly over melodramatic. Regarding the 'safari is not responding' horror we all experience to varying levels their response was as follows:
Thank you for your email. We are always grateful for your feedback. We are aware of the challenges with VoiceOver not responding in Safari, and are investigating solutions for a future software update.
So, though safari may not be responding, at least apple accessibility are. Good to hear that they are working on the problem. Fingers cross that they're will indeed be a fix at some point.