Currently we are adding all TabbedPanes to the DOM regardless of whether they are active or not. If we were to change this to only mount the active child to the DOM (so only render the active child) it would allow the DOM tree to be smaller and child components would have their React lifecycle methods called at more appropriate times.

Is there any reason that i'm missing for doing it way it currently is?

This came about because of this google groups posting: https://groups.google.com/forum/#!msg/reactjs/fl0z5CZg-BY/tpE5s0-4r_kJ