title: why is cygwin so slow
body: <p>I run a script on Ubuntu, and tested its time:</p>
  
  <pre><code>$ time ./merger
  ./merger  0.02s user 0.03s system 99% cpu 0.050 total
  </code></pre>
  
  <p>it spent less than 1 second.
  but if I used cygwin:</p>
  
  <pre><code>$ time ./merger
  real    3m22.407s
  user    0m0.367s
  sys     0m0.354s
  </code></pre>
  
  <p>It spent more than 3 minutes. 
  Why did this happen? What shall I do to increase the executing speed on cygwin?</p>