This is a heavily optimized CPU miner for 6857coin for Spring 2016, which involves finding partial SHA256 3-collisions. It uses a simple algorithm of maintaining a large table of preimages, indexed by the lower few bits of the hash.
This miner is multithreaded and vectorized with AVX2 instructions to compute 8 hashes in parallel per core. For optimal performance, an Intel Haswell (or newer) CPU and 12 * 2^(difficulty * 2 / 3) bytes of RAM are required, although the memory footprint can be reduced in exchange for longer runtimes. This achieves about 140 million hashes per second on an Intel 12-core 2.5GHz Haswell-EP CPU with 16GB of memory.