take a breath so that pending repaints get some cpu time before the upload starts
function doSubmit() {
      // make sure form attrs are set
      var t = $form.attr('target'), a = $form.attr('action');

      // update form attrs in IE friendly way
      form.setAttribute('target',id);
      if (form.getAttribute('method') != 'POST') {
        form.setAttribute('method', 'POST');
      }
      if (form.getAttribute('action') != s.url) {
        form.setAttribute('action', s.url);
      }

      // ie borks in some cases when setting encoding
      if (! s.skipEncodingOverride) {
        $form.attr({
          encoding: 'multipart/form-data',
          enctype:  'multipart/form-data'
        });
      }

      // support timout
      if (s.timeout) {
        setTimeout(function() { timedOut = true; cb(); }, s.timeout);
      }

      // add "extra" data to form if provided in options
      var extraInputs = [];
      try {
        if (s.extraData) {
          for (var n in s.extraData) {
            extraInputs.push(
              $('<input type="hidden" name="'+n+'" value="'+s.extraData[n]+'" />')
                .appendTo(form)[0]);
          }
        }

        // add iframe to doc and submit the form
        $io.appendTo('body');
        $io.data('form-plugin-onload', cb);
        form.submit();
      }
      finally {
        // reset attrs and remove "extra" input elements
        form.setAttribute('action',a);
        if(t) {
          form.setAttribute('target', t);
        } else {
          $form.removeAttr('target');
        }
        $(extraInputs).remove();
      }
    }