Thinking better doesn't mean thinking harder.
When it comes to cognitive efficiency, don't think smarter, think attitude.
Here researchers found that personality traits particularly associated with "sensitivity to cues of reward" were better predictors of cognitive efficiency on a working memory task than behavioral performance or even measure of fluid intelligence (Raven's). If you were more cued to the reward of the task, your brain (actually your cingulate, prefrontal, and parietal cortex) didn't have to work as hard to achieve the same result.
In the figure below, researchers saw that extroverts activated their right prefrontal cortices and reward centers more with humor. The right prefrontal area is useful for all sorts of thinking and problem solving (for instance, the Tower of London, creative writing, inference, pattern formation).
What does this mean for us poor introverts? It means it's even more important for introverted or neurotic folks to find something that they find personally rewarding or motivating. When we love it, the thinking gets easy, pieces fall together, and we're in 'flow'.
Personality and Cognitive Efficiency
Personality, Humor, and Reward
Right Prefrontal - Finding and Retrieving Patterns
Right Prefrontal - Creative Writing in Your Brain
Right Prefrontal - Visual Spatial Decision-Making
Personality Types Gifted Students