You're confusing "brain" and "intelligence". A brain will be engineered to begin with. Then is has to learn. Once it learns some amount of information, it is in

You're confusing "brain" and "intelligence". A brain will be engineered to begin with. Then is has to learn. Once it learns some amount of information, it is intelligent, and this intelligence can be cloned. However, to increase its intelligence, that brain has to start learning again. And this process can be slow, because it is limited by the speed of experimentation. I agree that the machine will probably be able to learn faster than humans, but it's not at all clear how much faster. Also, we know little about human intelligence. For example, Einstein's brain wasn't much bigger or faster than an average human brain, yet he could make profound discoveries. It's not clear to me that if you take an average brain, and make it faster/bigger, it will suddenly be able to make scientific breakthroughs.