x.innerHTML is a DOM operation too. I would think you want to differentiate between doing an "innerHTML" operation and "other DOM operations" That said, constr

x.innerHTML is a DOM operation too. I would think you want to differentiate between doing an "innerHTML" operation and "other DOM operations" That said, constructing HTML as a string and using one innerHTML call is much faster than doing createNode/appendChild multiple times. DOM operations are definitely the bottleneck when it comes to performance : The less of them you do, the better off you are. (I learnt my lesson the hard way)