[boubiyeah]

What could possibly be done in the React.js version to make its performance closer to Mercury/Elm? I notice some 'shouldComponentUpdate' methods are already overwritten.

Or is this the limit of an overly mutable language like js?

[boubiyeah]

After investigation, it turns out react has the potential to be faster than Om if it fixed its batched updates. Another huge performance issue is Function.prototype.bind which is called extensively.

The Om example does some kind of Event delegation using channels which is much faster.