But this is apples and oranges. Process 1 creates and calls lambdas, etc.

A proper comparison could be:

  # Case 1.
  for n in range(len(data)):
    data[n] = transform1(data[n])
    data[n] = transform2(data[n])

  # Case 2.
  for n in range(len(data)):
    data[n] = transform1(data[n])
  for n in range(len(data)):
    data[n] = transform2(data[n])