Fast persistent data structures, combined with the idea of "reference types" that encapsulate mutation points when you really need them. http://www.infoq.com/p

Fast persistent data structures, combined with the idea of "reference types" that encapsulate mutation points when you really need them. http://www.infoq.com/presentations/Value-Identity-State-Rich-Hickey http://www.infoq.com/presentations/Value-Identity-State-Rich... So yes in Om there is a single mutable point which then points to the current immutable tree to be used for rendering. This is very fast. Clojurescript performance is not a bottleneck, most of the time is spent within React.