Frosting: The Need for Speed

I just made a few more batches of frosting and think I've figured something out; the trick is to make it quickly.  The recipe I use is:

6 T margarine or butter

4 1/2- 4 3/4 powdered sugar

1 1/2 t vanilla

1/4 C milk

Mix margarine in mixing bowl until fluffy.  Gradually add half of powdered sugar.  Then add milk and vanilla, then the rest of the sugar, adding more milk if necessary to reach spreading consistency.

I never have to add milk.  This recipe is supposed to frost two small layers of cake, one 9x13, 24 cupcakes, etc.  If you like to pile on frosting like I do, it only frosts 12.  Yum.

So today I made two batches right in a row; one I kept the blender on quite a bit, and was a little slower; the second, the butter whipped up quickly and the whole process took about 4 minutes.  I tried the same method of piping on the frosting for the first and second batches and got the result on the second.  I've learned something.  

Cupcakes on R are batch 1; cupcakes on L are batch 2.  Batch 1's icing fell right away; batch 2's was just firmer and still looks exactly the same 10 min. later.