title: fast data move from file to some StringIO
body: <p>In Python I have a file stream, and I want to copy some part of it into a <code>StringIO</code>. I want this to be fastest as possible, with minimum copy.</p>
  
  <p>But if I do:</p>
  
  <pre><code>data = file.read(SIZE)
  stream = StringIO(data)
  </code></pre>
  
  <p>I think 2 copies was done, no? One copy into data from file, another copy inside <code>StringIO</code> into internal buffer. Can I avoid one of the copies? I don't need temporary <code>data</code>, so I think one copy should be enough</p>