Or did it just move somewhere I can't find it?
The external build option never worked well for me with IDEA 12 and appears to completely fail under 13.
It immediately used up all heap in both the IDE and compiler processes, goes through cleaning and parsing phases fine, - then doesn't appear to doing anything much with the CPU and just says "writing classes" for as long as I had patience to sit and wait for it.
It's probably something to do with my environment (crappy windows XP SP3 environment, running all manner of virus scanners and other enterprise cruft).
But first things first: can I go back to the old way?