Earlier quoted context omitted.
We will have something that we ourselves define to be AGI, sure, but then it's easy to hit any goal that way. Is that machine really intelligent? What does that word even mean? Can it think for itself? Is it sentient? Similar to AI, AGI is going to be a new industry buzzword that you can throw at anything and mean nothing.
From the point when an AGI is capable of constructing a slightly better version of itself and has the urge to do so, everything can happen very fast.
Once developed, one solely needs to turn up the execution rate of an AGI, which would result in superhuman performance on most practical and economically meaningful metrics.
Imagine if for every real day that passed, one experienced 100 days of subjective time. Would that person be able to eclipse most of their peers in terms of intellectual output? Of course they would. In essence, that's what a speed superintelligence would be.
When most people think of AI outperforming humans, they tend to think of "quality superintelligences", AIs that can just "think better" than any human. That's likely to be a harder problem. But we don't even need quality superintelligences to utterly disrupt society as we know it.
We really need to stop arguing about time scales for the arrival of AGI, and start societal planning for its arrival whenever that happens. We likely already have the computational capacity for AGI, and have just not figured out the correct way to coordinate it. The human brain uses about 20 watts to do its thing, and humanity has gigawatts of computational capacity. Sure, the human brain should be considered to be "special purpose hardware" that dramatically reduces energy requirements for cognition. By a factor of more than 10^9 though? That seems unlikely.