> it's not uncommon for even a simple/naive/asymptotically less efficient algorithm written in Asm to outperform a more complex/clever/asymptotically efficient

> it's not uncommon for even a simple/naive/asymptotically less efficient algorithm written in Asm to outperform a more complex/clever/asymptotically efficient one in an HLL at the problem sizes encountered in practice, simply by virtue of the constant factor being much smaller You're conflating two different things: constant factors based on algorithm choice and the merits of hand-written assembler. It's true that sometimes asymptotically worse algorithms beat asymptotically better ones in practice. It's a lot less clear that humans can regularly beat compilers for typical scalar code.