Javascript function-in-function performance

case1.js

var a = function (v) {
    function b (v) {
        return 42;
    }
    return b(v);
}

var start = (new Date).getTime();

for (var i=0; i < 1e6; i++) {
    a(i);
}

var t = (new Date).getTime() - start;
console.log(t); //122 ms - slow, because each time a() is called - b() seems to be redefined

case2.js

function b (v) {
    return 42;
}

var a = function (v) {
    return b(v);
}

//----------------------------------------------

var start = (new Date).getTime();
for (var i=0; i < 1e6; i++) {
    a(i);
}
var t = (new Date).getTime() - start;

console.log(t); //17 ms - fast - because b() is defined only once

case3.js

var a = function (v) {
    var namespace = {
        b : function  (v) {
            return 42;
        }
    }
    return namespace.b(v);
}

//----------------------------------------------

var start = (new Date).getTime();
for (var i=0; i < 1e6; i++) {
    a(i);
}
var t = (new Date).getTime() - start;

console.log(t); //55 ms - the hell why is it faster than case1.js???

gistfile1.txt

In this gist I tried to compare the performance of private functions in JS.