We have seen DOM caching before and function delegation is also a kind of function caching. Take a look at the following snippet:
for(var i=0; i<count; ++i)
    $get('divContent').appendChild(elementsIdea);
As you can figure out the code is going to be something like:
var divContent = $get('divContent');
    
for(var i=0; i<count; ++i)
    divContent.appendChild(elementsIdea);
That is fine, but you can also cache browser function like appendChild. So, the ultimate optimization will be like the following:
var divContentAppendChild = $get('divContent').appendChild;
    
for(var i=0; i<count; ++i)
    divContentAppendChild(elementsIdea);