about jQuery.parseJSON

about jQuery.parseJSON

when I see the codes below:
  1. return window.JSON && window.JSON.parse ?
  2. window.JSON.parse( data ) :
  3. (new Function("return " + data))();

I think the the 
  1. (new Function("return " + data))();
is slower than use eval directly, it may be improved this way:
  1. ( eval( "["+data+"]" ) ) [0]