title: Why reading is done at random speeds when using createReadStream (file reading) on local node?
body: <p>I am using <code>createReadStream</code> api to read huge data from a file.
  Sometimes it takes 7 seconds to read while sometimes it takes 30 seconds to read.
  I would like to understand why it is taking more time to read the same file with same data in some instances while it is taking less time in few instances. Why it is not fixed time as I am reading the same file with same data?</p>