Imagine casting a "speed ×100" spell on a dumb person. Would that make them a smart person? No.
On the other hand, if we would cast a "speed ×2" spell on a smart person, it would appear to make them smarter. They would be able to solve difficult problems in half the time, right?
So... there seems to be some connection, but also a difference. Speed can make you more productive, and productivity is a signal of intelligence. But if you make systematic mistakes in thinking, you will only be making them faster.
Smart people in the technology world no long believe they can think their way to success.
Because they already are thinking. If you are already thinking at near 100% of your capacity, telling you "think more" is not going to help. The right advice in that situation could be "instead of thinking without experimenting, try thinking and experimenting". But one should give that advice only to people who are already thinking.
The Law of the Minimum seems metaphorically relevant. "Growth is controlled not by the total amount of resources available, but by the scarcest resource."
Intelligence, speed, time, energy, charisma, money, able-bodiedness, a like-minded community, etc.: any of these may be someone's limiting factor.
From Scott Adams Blog
The article really is about speeding up government, but the key point is speed as a component of smart:
This shifts the focus from the ability to grasp and think through very complex topics (includes good working memory and memory recall in general) to the ability new topics quickly (includes quick learning and unlearning, creativity).
This also changes the type of grit needed. The grit to push through a long topic versus the grit try lots of new things and to learn from failures.