how value expression<action<t>> movement quickly?

suppose have following code:

expressionhelper.getroutevaluesfromexpression<accountcontroller>(ax => ax.myaction("a", "b"));

(from asp.net mvc futures assembly). slight graceful quick - executes 10k iterations 150ms.

now, change formula this:

string = "a";
string b = "b";
expressionhelper.getroutevaluesfromexpression<accountcontroller>(ax => ax.myaction(a, b));

this formula govern 10k iterations 15 seconds

the problem following code:

expression<func<object>> lambdaexpression = expression.lambda<func<object>>(expression.convert(arg, typeof (object)));

func<object> func = lambdaexpression.compile();

value = func()

is there improved proceed value countenance compiling countenance each time? severely impact asp.net mvc couple date speed.