You'd be surprised how many workloads end up spending large amounts of time in memcmp / strcmp. The chief advantage of big-endianness is that a 64-bit read is already in the order necessary for strcmp or memcmp. This means you don't need specialized instructions for fast strcmp / memcmp. Though, I would guess in a pipelined implementation with good pre-fetch logic, you'll usually not pay any time penalty (and only a single instruction in size penalty) for a byte order swap instruction in the middle of strcmp / memcmp.