Still daily driving the 6s after almost 11 glorious years, and I can't imagine software ever being painfully slow on M series hardware. But if you need, well, are forced, to be on latest MacOS, then you are out of luck and you have my sympathy.

(My relatives iPhone updated and its just bad all around. And with increased font size for accessibility, elements don't cover all the text. Feels rushed and not the promised Apple land.)