IQ only relatively effects ones ability to quickly grasp and act on log based concepts. Having an average IQ (aka, 100) would loosely mean you learn at an average rate. Even then, this takes into no account your studying habits, degree of topic immersion, and grasp of relevant material. Someone with high IQ, but bad studying habits, minimal exposure to a topic, and low understanding of related topics would potentially learn slower than someone with the opposite scenario.
Long story short, you're putting way too much emphasis on IQ when it holds little to no true bearing in relation to a person's entire lifespan with their ability or lack thereof to understand topics.