title: debug performance diff of Same code on nearly same cpu/ram
body: <p>I wrote a machine learning model which involves quite amount of numerical optimization computation, it's in Python with <code>Numpy + Scipy.optimize</code>.</p>
  
  <p>The training process is very slow on a Lenovo Thinkpad X220 (with i5-2520M CPU and 4GB RAM, Ubuntu 14.04 OS), but much faster on a Lenovo Thinkpad X240 (with i5-4200U CPU and 4GB RAM).</p>
  
  <p>I compared the 2 CPU's online, X220 CPU (i5-2520M) has higher operating frequency, but X240 CPU (i5-4200U) has <code>Haswell</code> arch. So the performance should pretty much the same, right?</p>
  
  <p>I wonder that why the Python code is so slow on X220 is because the numerical optimization or matrix calculation library is poor on Ubuntu, how should I debug this performance prolem?</p>