[r-t] Parallel searches [was Exhausted search spaces]

[Graham John]

MBD wrote:

> It might be worth worrying a bit about the size of
> the state frame you have to copy to a forked processor.

Yes, there is probably a significant overhead in checking whether there is a
processor free too, but this is just optimisation of the algorithm.

> You can carry out maybe ten thousand arithmetic
> operations in a microsecond. Awesome.

Indeed, as illustrated by a search for Cambridge Minor extents. SMC32
completes the search before its clock has ticked over the first millisecond.

Graham