function declaration faster than function expression?

The difference b/w function declaration & function expression is beautifully described in var functionName = function() {} vs function functionName() {}
In this it's mentioned that function declaration is evaluated during parse-time, & function expression is evaluated in the execution-phase

In bytes.com it's mentioned that function declaration is faster than function expression.

I created a basic test case for this: http://jsperf.com/function-declaration-vs-function-expression

Function Declaration:

function myfunc() {
 alert("yo");
}
myfunc();

Function Expression:

var myfunc = function() {
 alert("yo");
}
myfunc();

The test showed that function expression is 90% slower than function declaration.

Why such a difference in speed?

Edit:
From the results in http://jsperf.com/function-declaration-vs-function-expression

In Chrome, IE9, Opera & Safari -> Function Declaration is faster than Function Expression

In Firefox, IE7, IE8 -> Function Expression is faster than Function Declaration

In IE9 Function declaration is faster, whereas in IE 7 & 8 function expression is faster. Is it because of change in JavaScript engine in IE9, or was this move intentional?