Searching all of memory for a given bitstring is indeed very quick -- a few seconds. But,
err, if you already know what the bitstring for the key is, why are you searching for it?
What you'd really be searching for would be the data structure that's holding the key -- the
OS has some way to figure out which random-looking bitstring in those gigabytes of memory is
really the key, so you can too, by finding the right data structures and chasing the right
pointers. AFAICT that means that the techniques you're suggesting won't work -- if the key is
split into multiple pieces, then don't look for the pieces, look for the data structure that
lists off where all of the pieces are so they can be found again by the OS.