and can therefore immediately dismiss a staggering number of plausible courses of action (which by definition a domain-general mechanism would have to examine one by one) for one or a few favoured alternatives. For this reason domain-specific mechanisms are faster and more effective than their domain-general counterparts and we should expect natural selection to have favoured them.
The author explains that domain-specific mechanisms are faster and better than their general counterparts because they can quickly eliminate many potential solutions, while domain-general mechanisms have to consider each option individually. This is due to the fact that natural selection favors efficient solutions.