title: why is converting strings to ints in my lambda function slower than converting with list comprehension
body: <p>I have used the following two methods ina Codeeval problem,I used the first method originally and thought I could speed it up by removing converting strings to ints from the lists to the lambda but it actually slowed the code down considerably, why is this so?</p>
  
  <pre><code>with open("multiply.txt") as f:
      for line in f:
          line1 = line[:line.find("|")].split()
          line2 = line[line.find("|")+1:].split()
          line1_int = [int(x) for x in line1 ]
          line2_int = [int(x) for x in line2]
          mult= map(lambda x, y: x*y, line1_int, line2_int)
          print " ".join(str(s) for s in mult)
  
   with open("multiply.txt") as f:   
      for line in f:
          line1 = line[:line.find("|")].split()
          line2 = line[line.find("|")+1:].split()
          mult= map(lambda x, y: int(x)* int(y), line1, line2)
          print " ".join(str(s) for s in mult)
  </code></pre>