Is this question related to the range problem, by chance? It is true that in a tailwind you maximize the benefit to range by flying an IAS a tad slower than the still air range speed and in a headwind you minimize the loss by flying a tad faster. I ask just to clarify the ground rules.
If this is a pure windshear or microburst question then it has already been answered. Sudden headwind gives transient increase in IAS, more lift etc and sudden tailwind gives a transient drop in IAS, loss of lift etc.
Dick W