The best-known tmto algorithm is 20 million times slower with 1 millionth' the memory.
Of course, even being just 200 times slower means you will rarely find a block
if the block interval is just 100 proof attempts long...
This is where we stopped the last time - I claimed that it's not a problem for a QC to do 20 million computations at once (25X qubits is enough to do a computation on 33 million sets of data). In this situation someone ought to prove that that particular algorithm is quantum-resistant, otherwise we can't accept that PoW blockchain are secure (burden of proof in cryptography lays on one claiming that an algorithm is secure, not the other way around).