[bayesian_horse]

It is theoretically the case, that a virtual DOM implementation has to do more work than a perfectly efficient manual (or automatically generated) DOM mutation.

However, in practice the difference hardly matters and it is really hard to do efficient DOM mutation correctly. Which is why virtual DOM approaches are at the heart of most of the modern frameworks...

[mosdl]

They are at the heart because it allows people to write code faster while being OK with the perf/mem hit. But in the end its always less efficient which is why you have to hand wave it away.