Human Metro Map and Performance Management

In my Guerrilla classes, I like to compare making a computer performance model (e.g., in PDQ) with model train construction. In the latter case, the goal is to make a scaled replica that includes as much realistism as possible (Aside: I'm assuming this is true, since I have no interest in making model trains). The goal for a performance model is the exact opposite, viz., to throw away as much detail as possible, while still maintaining the essential performance characteristics of the real computer system.

This notion leads to Guerrilla Mantra 2.4:

A performance model is more like a map of a metro rail system than a scaled replica of the metro railway.