Can a person be brilliant even though slow at resolving problems?
There are many definitions of intelligence. I find the one given by David Wechsler (1944) useful in the context of this question:


  The ... capacity of the individual ... to deal effectively with his environment


Finding a solution quickly is sometimes necessary if you want to deal with your environment effectively. Not all problems will wait for you to solve them slowly. Which is why the concept of intelligence usually includes a time component and a person solving the same problem slower is considered less intelligent.

"Brilliance" is not a psychological concept.



Source:


Wechsler, D (1944). The measurement of adult intelligence. Baltimore: Williams &amp; Wilkins.