How does the Hip hop virtual machine (HHVM) theoretically improve PHP runtime performance?

8 months ago

WilliamTi
Member | 2
+
-2
-

From a high level, how does Facebook, et. al use to improve PHP performance with the Hip Hop Virtual Machine?

How does it differ from executing code using the traditional zend engine? Is it because types are optionally defined with hack which allow for pre-optimization techniques?

My curiousity arose after reading this article,