title: + [NSString stringWithContentsOfFile:] performance
body: <p>I need to load files in iOS, now I use the <code>+ [NSString stringWithContentsOfFile:]</code>.
  The files are mostly 500kb to 5mb.
  I load an approx. 4mb large file and Instruments and stopwatch told me it needs 1.5 seconds to load this file. In my opinion its a bit slow, is there a way to get the string faster?</p>
  
  <p>EDIT:</p>
  
  <p>I try some things and notice now, the creation of the NSString is my problem it takes 97% of the time and not the real loading from disk.</p>