[fanf2]

My qp trie code <http://dotat.at/prog/qp/> got a performance boost of about 20% by adding prefetch hints in the obvious places. The inner loop is fetch / compute / fetch / compute, chaining down into the true. The next fetch will (usually) be some small offset from a pointer we can get immediately after its preceding fetch, so prefetch the base pointer, then compute to work out the exact offset.