It seemed nontrivial to reduce the number return continuation pmc's used in oofib.imc. So I instead added an _extra_, unused one, to the two already used in each fib method.
Parrot ran 30% slower. (Optimized, unoptimized, and jit) Which suggests return continuation pmc driven memory management costs (gc and allocation) are currently a major, perhaps even dominant, factor in method invocation speed. Mitchell
