It might be best to not get into the details here - and recommending people start with 5 second is sort of an arbitrary number. For instance, some people might want to use 1 minute batches, or 10 minute batches, or whatever due to the way they build their application.

What I would do is add a sub-section in performance tuning that says "How to chose a batch interval" and explain the trade-offs. Then you can add a forward reference to that here and just say something like:

    Choosing a batch interval will depend on the latency requirements of your 
    application and the size of your cluster. See XXX for more details.