Dictation on macOS frequently stalls the computer

For the physically incapacitated, macOS dictation is a lifesaver.

However, I find that frequently using this utility grinds the system to a halt. Responsiveness goes down to 0 over a few seconds, the fan kicks in, I have to go to Activity Monitor and kill anything with the word ‘speech’ in it.

This feature has become completely unusable.

I’m considering a fresh installation of macOS.

But is there anything that can be done, short of this drastic measure?

And what can I do to debug this phenomenon? Simply reinstalling is not intelligently going to the root of the problem. So how to go to the root?