The store is usually pretty flat. Mostly a single object with a bunch of properties, some of which might be objects themselves. All of them are usually switch statements, and if the action isn't matching anything in the switch, it returns the default. Sometimes there are nested switches.

So realistically, considering the construct in play, you can do tens of thousands of calls to the reducers to get a new state every second.

That's not gonna be the bottleneck.