performance - Does var keyword in C# cause boxing?

Question

My boss forbids me to use var as it would cause boxing and slowing down the app.

Is that true?

Answer 1

An approach that might work is to write these two methods:

public static void WithInt()
{
    int x = 5;
    Console.WriteLine(x);
}

public static void WithVar()
{
    var x = 5;
    Console.WriteLine(x);
}

Compile, and use ildasm to examine the produced CIL. Show your boss.

edit @ck has done all but the last step for you :)