I can believe that. But the fact that this was done on a Threadripper 3990x, a high-core count (but slow interconnect / core-to-core communication) kind of com

I can believe that. But the fact that this was done on a Threadripper 3990x, a high-core count (but slow interconnect / core-to-core communication) kind of computer, makes me believe that there's a degree of parallelism in this problem. Otherwise, another computer (ie: higher GHz / less core count) could have been used instead. --------- I really don't know this specific algorithm: ECPP. It comes down to how that works... especially its parallelization.