dom tree caching performance: array v. linked list. see also: http://jsperf.com/dom-trees/

bookmarklet.js

javascript:with(document)(body.appendChild(createElement('script')).src='https://gist.github.com/raw/946036/8b51f04a6f9dbe15f5c375ac872a9ae56d4b8732/domTrees.js')._

domTrees.js

var t, count, node1, node2

function Node1(node) {
 this.node = node;

 var children = node.childNodes,
     i = this.length = children.length;

 while (i--) this[i] = new Node1(children[i]);
}

Node1.prototype.count = function() {
  var ret = 1, i = this.length;
  
  while ( i-- ) ret += this[ i ].count();

  return ret;
}

function Node2(node) {
 var first = node.firstChild,
     next = node.nextSibling;

 this.node = node;
 this.first = first && new Node2(first);
 this.next = next && new Node2(next);
}

Node2.prototype.count = function() {
  var ret = 1;
  
  if ( this.first ) ret += this.first.count();
  if ( this.next ) ret += this.next.count();

  return ret;
}

t = Date.now()
node1 = new Node1( document );
console.log( "time to create (Node1)", Date.now() - t )

t = Date.now()
count = node1.count()
console.log( "time to count (Node1)", Date.now() - t )
console.log( "nodes counted (Node1)", count )

t = Date.now()
node2 = new Node2( document );
console.log( "time to create (Node2)", Date.now() - t )

t = Date.now()
count = node2.count()
console.log( "time to count (Node2)", Date.now() - t )
console.log( "nodes counted (Node2)", count )