"I need to reduce the term scalability to its core concern: performance"
With that statement, the article went from interesting to uninteresting.
Performance is not really that important. There will always be faster machines with more RAM. You can load balance across machines, that is not really a language issue, although some support it better than others.
Maintainability is the key to any large software development project. If you have 100,000 lines or code in a mid-sized project, you definately want a language that provides the best concepts and tools to manage that complexity.
I am not a PHP user. I believe that PHP is behind Java in maintainability, but I don't know PHP well enough to compare them point by point, and I may consider using PHP on a future project so I want to know how far it is behind. How does PHP compare to java's packages, jar files, war files, import statement, class visibility, interfaces, reflection, javadocs, UML tools, etc. Now that would be a more useful article.