speed optimization for javascript innerhtml

innerHTML is already pretty fast...is this really warranted?

This is much faster than using (el.innerHTML = value) when there are many
existing descendants, because in some browsers, innerHTML spends much longer
removing existing elements than it does creating new ones.

function replaceHtml(el, html) {
    var oldEl = (typeof el === "string" ? document.getElementById(el) : el);
    /*@cc_on // Pure innerHTML is slightly faster in IE
 oldEl.innerHTML = html;
 return oldEl;
 @*/
    var newEl = oldEl.cloneNode(false);
    newEl.innerHTML = html;
    oldEl.parentNode.replaceChild(newEl, oldEl);
    /* Since we just removed the old element from the DOM, return a reference
 to the new element, which can be used to restore variable references. */
    return newEl;
};

References

1. faster-than-innerhtml