These are the precautions given to Spitfire pilots facing the Fw 190:
Essentially the advice was to cruise as fast as possible, especially in the danger zones where Fw 190s were expected, partly because the Spitfire was slower to accelerate than the 190.
As for claims that the Bf 109E generated less drag than the Spitfire I - there has been no objective data presented to prove this, but here are the figure for the Spitfire I:
