There's problems you can solve quickly, and problems that you can solve at all. You want to find someone who can solve problems at a certain difficulty as fast as possible. If they can't solve it, work on making it so they can. If they can, work on making it so they do what they already can do, but faster.
This is particularly clear with computers. You can write better algorithms that solve more problems and get better answers, at the cost of running slower. If a program can't solve your problem, it's worthless. If it can solve your problem, making it more sophisticated will make things worse. For example, you can't stick formatting into a .txt file, but if you have no need for formatting, Notepad runs faster, takes less space, and is more reliable than Word.
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.