Relationship between processing speed and IQ in twice exceptional children How come some twice exceptional children (i.e., intellectually gifted children who have some form of disability) have high iq, but low processing speed? Isn't processing speed a factor of intelligence? If not, why do iq tests have a time limit?
This is not an answer to your question but you probably want lookup Howard Gardner and his theory of Multiple Intelligence (MI).

The basic proposition here is that the IQ test (origins in the work by Alfred Binet) is not a wholistic measure of intelligence and that it measures the ability of one to think in a certain expected way.  Gardner proposes that there are many ways to think (and thus how one learns) and he comes up with 7 distinctly different types of intelligence (his later work adds more).

I'm not familiar with your child subjects, but in comparison if you measure IQ of some Autistic children they may measure extremely high IQ, but may be perceived as slow or unresponsive to other tasks like social interaction (or low "EQ").  This does not mean that they are either intelligent or not intelligent, just that they think in a different way than the observer.

Speed (and age) is a factor of intelligence, but irrelevant if the underlying measure is fundamentally flawed.  For example, you can be quick at maths or slow at maths, this will just tell you if you are intelligent at mathematical thinking.  But it will not tell you is your are "intelligent" because you could be quick to learn music rhythms (thus musically intelligent) but this is not measured in IQ.