Go faster
Raw throughput: the craft below the algorithm (lookup tables, cache-sized structs, generated code) and spreading the work across many machines. It decides whether a node costs 26 cycles or 2,600, and it is the clearest demonstration that speed alone does not move the wall.
Every record solver runs the same depth-first backtracker. What separates them is the layer underneath: lookup tables, perfect hashes, cache-sized structs, generated code, compiler archaeology. That craft decides whether a node costs 26 cycles or 2,600. The community's twenty-year engineering ledger, technique by technique, and what it all bought.
Every few years the community threw more computers at Eternity II: BOINC screensavers, prize-sharing syndicates, PlayStation clusters, scavenged single-board farms. What 10^19 operations bought, how a depth-first search actually gets partitioned, and the one job distribution turned out to be good at.