I saw you discussing this and there are a couple issues. You do realize you are searching a puzzle and range that was solved.
I appreciate the concern. This is how I test the software, this is needed before it goes onto a large cluster to make sure it is actually working and produces known result. Consider this being a sanity check like 2+2 should produce 4.
It is possible to get billions of keys per sec on midrange store bought pc. There are way better methods than what you are using. If you are interested in getting involved in the puzzle there are much better ways with much better results even using cpu. To hit billions you need to use a GPU a 3060 or equivalents will hit billion+ per second. If advanced you can get it up to 10 billion with more advanced methods. Look at kangaroo and bitcrack and vanitysearch.
I appreciate the concern #2! None of the machines that run the code have the GPUs in them, the hardware is quite old. However, the cluster size is currently 985 systems, each has 2x 2650v4.
CPU Threads : 48
Mkeys/s : 76.83
This is (76.83 * 985) / 1000 = ~75.67 Gkeys/s