[Dylan16807]

> My binary implementation was probably spending almost all of its time waiting to read or write numbers from RAM due to L1 cache misses. I did not know at the time how to actually test this, but I thought let's try a more memory efficient version anyway and see if it improves things.

The text never comes back to this, but the answer is that a handful of 1-2KB numbers fit into L1 just fine, and even if they didn't there's a megabyte or more of L2 that takes about 3ns to access.

> It goes without saying that probably none of this is actually cryptographically secure, but that was never the point anyway.

Hmm. This is just the prime generation, so it avoids most RSA pitfalls, and urandom had better be secure. So if this code works at all then there's not much that could go wrong. RSA has a few issues with weak primes to avoid but I don't know if they're likely enough to matter here.