The tough problems that take most of the time are the design and theoretical understanding of the problem. The actual tools used to implement the solution, while not trivial in their differences, are never as important as fully understanding the problem and having a good architectural design.

Or put differently, if you found me the fastest, most knowledgable person in the world with PHP web development, and then found the same guy for Scala, my assumption is they would both build a particular project in the same amount of time, all other things equal. And I could guarantee that one of the two wouldn't be "dozens of times faster" than the other.