I was reading up on whether it was possible to get faster performance on key generation and came across this post https://crypto.stackexchange.com/questions/29885/can-a-billion-elliptic-curve-keys-be-generated-on-a-laptop-in-less-than-an-hour

The very last post claims pretty high numbers and wanted to know if it was bull or real. If it's real what would the math be for those kinds of speeds? And what is referred by "symmetrie" of seck256k1?