title: Why are NumPy arrays so fast?
body: <p>I just changed a program I am writing to hold my data as numpy arrays as I was having performance issues, and the difference was incredible. It originally took 30 minutes to run and now takes 2.5 seconds!</p>
  
  <p>I was wondering how it does it. I assume it is that the because it removes the need for <code>for</code> loops but beyond that I am stumped.</p>