It's an exponential speedup. The virtual DOM is a tree, and if roughly balanced, the path that needs to be updated is of size log(N) compared to the full tree

It's an exponential speedup. The virtual DOM is a tree, and if roughly balanced, the path that needs to be updated is of size log(N) compared to the full tree of size N that will be updated by default. In practice, it's the difference between a stuttering app that lags at every keypress in an input field, and something usable.