You meant 8 TK/s, or maybe 16 TK/s. It all depends on how fast you want something solved, if enough resources are available

VanitySearch from JLP, untouched sources, can do 9.3 GK/s, with a proper grid size, on a RTX 4090. Does that help with anything for puzzles? Not really, since only 1/6 of the hashes are for keys in a given range. That's why there's Keyhunt-CUDA and many other options. Are they not good or fast enough? Write your own, adapt it to your needs. It's like asking for someone to chew your food for you - they have better things to do with their time.

There is no voodoo secret method to speed up things, just coding skills to maximize hardware resources use to their best. That's what efficiency means, in the real world. You still need 500.000 to 1 million $ to have more than 50% chances to solve 68, no matter what you use or how well it's optimized - there is no secret weapon of salvation. And you have to be the first to find it as well.