When you have a ton of data that all needs to be processed, reactive programming makes the implementation easy to read, terse to write, and efficient to run. But when the data isn’t all needed, and processing the full stream is prohibitively expensive, more esoteric methods are necessary.

The following is a written draft of a speech I gave to a gathering of small group leaders at my church several months ago. After running across the file, I felt it might be encouraging for others to read.