Clicking start will schedule two self-restarting functions:
runSetTimeout uses setTimeout(fn, 0) for queueing itself
runHandleMessage uses postMessage for queueing itself
Results:
In IE10 Mobile, after a few seconds runHandleMessage is never called
In IE10 Desktop, after about 30s (once DOM manipulation has become slow enough) runHandleMessage is never called if you either: a) move the mouse around, or b) place the mouse on top of the changing log lines