Is the virtual keyword in Flex 3 a performance hit?

First of all, in ActionScript, you don't need to explicitly specify a method to be overridden as virtual, as in C #, the compiler will do it for you. This is why the keyword does not appear in any documents because it is irrelevant to the developer's perspective.

To answer your question, although that means overriding a method makes it slower, the answer is not until your class is sealed, which means you don't use the "dynamic" keyword when defining a class.

The reason is that when you build a private class, you will have explicit markers for each method for that object, when you override a method, you get a marker directly to the new function, the class should not look at this at runtime, as in a dynamic class.