For those who are interested the following Website Body (code) update, stops the inner sub-menu items from flickering as they are now not being closed and opened:
Code:
<script>
var collectionClassName = '.Menu';


function open(chain) {
  chain = chain.replace(/\s/g,'');
  var links = chain.split(',');
  var linkage = links.length - 1;


  $(collectionClassName).not(chain).hide('fast');
  
  $(links[linkage]).slideDown("slow");
  return;
}


$(collectionClassName).hide();
</script>
Acorn