It's been a while, I thought it was something to do with the blocks but it probably depends on what the exact state of the art is for cracking at this point. D

It's been a while, I thought it was something to do with the blocks but it probably depends on what the exact state of the art is for cracking at this point. Don't put it any higher than 4, that's for sure. In theory a parallelism on 1 should make it so the information required to do the next step has to be computed linearly (think of the dependency graph, it should look like a line instead of diverging then converging) but it's possible that either never worked or got cracked.